Questions to ask as you research solar energy and conservation.

  • Who is paying the cost of the Energy Audit ?
    • "He Who Pays The Piper Calls The Tune"

  • What is the motivation and bias of the source of funds for that "free" energy audit?

  • Since Air Leaks are proven to be the #1 cause of lost heating and air conditioning, what does a proposal to fix your problems do about air leaks?

  • When you bought a house, did the appraisal include an analysis of the cost of heating and cooling the house?
    • Was there a moisture test or mold test ?
    • Did that appraisal consider future energy inflation from Peak Oil and the upcoming demands of China and India for energy?

  • If you saved a lot of money on the wrong equipment or oversized equipment when not needed for a building's whose leaks have been repaired ... DID YOU SAVE MONEY?

  • Roof maintenance - are the panels somemone offering to install properly FLASHED so that the roof can be repaired or upgraded easily in the future?
    Solar Panel with flashing to enable roof shingle maintenance and replacement without disturbing the solar panel

  • Do proposals, appraisals and audits treat your house as a whole energy system? Be careful of discussions that only look at isolated areas that ignores the interactions of (for example) the fact that cellular shades can make the house much more comfortable with a lower heater or air conditioning consumption?

Appendix of concepts behind what we do at Commonwealth Solar.

Air Leaks are the easiest, most numerous and cheapest way to decrease waste

Air Leaks are #1 cause of lost energy

"Five Ways your Home Loses Heat"
Heat is lost to infiltration and air loss by over 3 times the amount it is lost due to ceilings. These categories generally stack up this way in terms of % heat loss in a home:
  • Infiltration / Air Leakage: 35%
  • Windows & Doors: 18%-20%
  • Floors & Below Grade Space: 15%-18%
  • Walls: 12%-14%
  • Ceiling/attic energy lost to conduction because of lack of insulation : 10%
(note: this last category of "ceilings" does not include leaks through microscopic cracks in the plaster, lifted drywall tape, moisture damaged disintegration, holes for light fixtures, leaks through penetrations for wires etc.)
The alternate EERE research shows similar air losses categorized differently
That is, put another way, insulation only insulates when air does not move through it.
Consider this example here of the green metal siding that obviously not only did not prevent air flow, it did not stop flying insects such as wasps from building their nests in the fiberglass "insulation" !
This insulation provided almost no benefit. Air filters for engines are sometimes made of fiberglass. Fiberglass provides no air barrier of its own.

Remember to compare these general percentages with the cost for each repair and keep in mind that blown cellulose insulation both insulates and reduces air leakage.
If a wasp can FLY into the insulation, you KNOW the air flows right through it - thus making the "insulation" worthless
Insulation only works if there is an effective air barrier.

Audit, Energy

An energy Audit is a detailed analysis of the hidden energy losses that can increase your monthly cost of living by as much or more than a car payment ! So ONE energy audit can save you many times the cost of a new car! Even more importantly, those air leaks sometimes exacerbate allergies to mold, vermin and dust as well as make you unecessarily uncomfortable.

An independent auditor is the best first investment during planning for building upgrades because that auditor works for YOU and not for a commission on a bigger heat pump or more expensive windows etc.

Some tips on getting started with your own lifestyle and building shell "tuneup" (audit).
Energy Star listing of "Common Problems" (most of which will be qualified and quantified by a thorough energy audit.
Energy Star on Audits

Dominion Home Energy Calculator

How much pollution does your energy consumption generate?
(note: to find how much pollution an alternative energy source would save, just plug in the estimated kWhrs of energy replaced by your alternative energy source instead)
Also this includes the power line losses (estimated for your location!)

Home Energy Saver - Do It Yourself audit guide

"Consumers don't want to buy electricity or fuel.
They want warm showers and cold beer !"

Amory and L. Hunter Lovins, Rocky Mountain Institute

Blower Door measures the air leakage of a house with CALIBRATED meters

Blower Door

Uses calibrated fans and meters to measure how MUCH your building leaks air. This give you the chance to see exactly how leaky or well sealed a house is. Then after work is done, can see how much the efficiency has been improved.
One caveat to remember is that this simulates a very windy day. There are some instances where a house can be leaky but if the leaks are protected from the wind, it will still hold heat. But a Blower Door is a great place to start with quantifying the effectiveness of your house for holding heat and AC in.

Any audits you get on your building should include the Cubic Feet per Minute and the calculated Air Exchange Rate that comes from using a Blower Door properly.
Did the audit include the CFM and air exchange rate (number of exchanges per hour.) ?


British Thermal Units. A unit of heat energy. To really compare energy options, it helps to have a standard measure. Generally everything is converted to BTU's or Joules of energy for comparison of options. Keep this in mind if someone says "years ago I only paid $x to heat my house. Ahh, yes, but what was the price per BTU ?

Cell Shades insulate your windows

Cellular Shades

Cell shades are like adding a styrofoam panel to your window ... in-effect superinsulating your windows. They can also come with a track to block air from flowing around the shades.

[Click here for a demonstration]

Cellular shades are especially helpful on the north side of a house where you do not get any solar gain in the winter and thus want to keep your heat in, but cellular shades can also help control excess heating from the Summer Sun and keep your AC inside and the Summer Heat out!

Commonwealth Solar can install cellular shades for maximum cost-effective window insulation.

Drain Back vs Glycol Loop

There are essentially two most common solar thermal options for Central Virginia.
Central Virginia has a freezing climate so any water left up in the panels at night in the Winter or even Spring or Fall will likely freeze and damage the pipes.

So option one is to have a sealed and pressurized loop like in your car that uses an antifreeze solution (typical ethelyne glycol or "food grade" Propylyne Glycol) that is filled all the time.
You should not drink antifreeze so a heat exchanger is absolutely required.

Option two is a "Drain Back" (not to be confused with "Drain Down") system.
As the name implies, as the sun and/or temperature in the panels goes down, the pumps stop and the water drains down into a holding tank that is safely within the protected shell of the building.
The pumps also stop when the tank has reached the high temperature cutoff point. The water in the panels drain back so that stagnation damage is far less likely.

Commonwealth Solar's drainback system has been tested by the state of Virginia* to collect and store more heat per square foot of collector than most systems and is not pressurized and so has less potential failure points than loop systems.

*John Randolph, Bob Schubert, Saifur Rahman, Yonael Tekiu, Virginia State Agency Solar System Monitoring and Evaluation: Final Technical Report , Virginia Polytechnic Institute and State University Blacksburg, Virginia prepared for Virginia Department of Mines, Minerals and Energy, Richmond, Virginia. May 1995


Heating and Cooling Ductwork is a MAJOR potential loss point for heating and air conditioning!
  • Air leakage through gaps in ducts. The heat is lost with the air moving (convection).
  • Air leakage through (convection) interface of duct to wall/floor/ceiling (registers)
  • Conduction of Heat through walls of ducts
Air leaks are the leading loss point for heating and air conditioning.
The first goal of any efficiency and conservation effort must include checking the ductwork for leaks.

Burying the ductwork where possible under cellulose insulation will help tremendously with both causes (conduction and convection) of heat loss from ductwork.

We have even seen very "affordable" installed ductwork that was LEFT WIDE OPEN, typically at the end of a house. We usually find those when the occupants complain that an end room seems to get little or no air flow from the registers.
But where the ducts are in the attic or even (horrors!) out in the outside air ... then proper testing, sealing and then insulating those ducts is vital.

If the house seems to be cheaper to heat with electric space heaters, this is a very important piece of evidence that your ductwork is hugely wasteful.

Two studies showed that ducted homes had 70 percent more air leakage and used 17 to 22 percent more energy for space heating.

  • Consider that the square footage of exposed air is often just as large in the ductwork as the entire ceiling of the building! The duct has four sides and travels the length and width of most buildings. In spite of this huge square footage of your conditioned air to the attic and/or outside air, most ducts have no insulation or only R3 for half an inch!

    So putting ductwork in the attic is like adding another whole attic of heat loss in the winter or heat load in the summer.  So a duct exposed to the heat and cold of an attic with no insulation or only R3 of an inch or fraction of an inch makes heating or cooling a  house with ducts in the attic like heating and cooling an entire additional building. Is your wallet up to that?
  • The solution is to either place the ductwork in the conditioned space (not in the attic) if you are installing a new system from scratch for an upgrade of a historic house or building a new building.
  • If the ductwork already exists in the attic, then seal and insulate as much as absolutely possible. Check that ductwork periodically because often some of the sealing will fail over time.
  • Also pay attention to how well sealed the registers are to the wallboards, ceilings and floors especially because a leaky return register can draw in air from the inside of the wall or even outdoors which might include mold, illness causing irritants like fiberglass fibers, and vacuum air from  the basement or crawlspace through  the inside of the wall where holes in the base allow air to come up from below.
Oikos noted that one study showed that "by repairing 43 percent of the duct leaks, they cut infiltration by 63 percent." and that "heat loss from the average ducted air distribution system reduces the overall system efficiency by 30 percent."

An independent auditor is the best investment because that auditor works for YOU and not for a commission on a bigger heat pump or more expensive windows etc.


Foam outside wall that will keep out freezing air temperatures in the Winter as well as a air and vapor barrier for leak reductions

Exterior Insulation

Usually a brick or concrete foundation and/or walls are insulated inside. However when possible, its actually better to insulate on the OUTSIDE.

Exterior Insulation usually with foam panels provides a wonderful opportunity to use the "thermal mass" of your building to your advantage. Thermal mass is any heavy mass (like the thick walls of older municipal buildings, or a cave, for example) that change in temperature very slowly. Thus as you go into Summer, the cooler condition of the thick walls decreases your need for Air Conditioning. And then as you enter Winter, the left over heat from the Summer decreases the rate at which your house cools off.

Insulating the outside of a thermal mass, that is, a thick brick or concrete wall and/or foundation now means that effect is amplified because you have insulated your walls from the extreme heat of early Summer and the extreme cold of early Winter. As you run your Air Conditioning or Heating, it is now heating a wall that averages the outside temperature as well as absorbing as a kind of "thermal battery" your efforts to cool or heat your house to the temperature you want.

An added benefit is that in some cases there are many microscopic holes in the mortar that allow diffused air to be drawn through the brickwork!
So instead of "pointing" the joints in brick, another option that gives you energy efficiency benefit is to put on exterior insulation.
(For example, in one blower door test, we found a steady blast of air coming down a chimney. This was in spite of the fact that the top of the chimney was capped solidly. It turns out the mortar had failed to some degree, it needed pointing, and so the air was coming into the house through the mortar!)


Financing your investment into being more healty, wealthy and wise with a more efficient building and then alternative energy production is a HUGE topic. This appendix entry only skims the surface.

The short version is that wealthy and healthy people combine
  • Luck (hey, you're HERE aren't you?)     with
  • preparation                  multiplied by
  • perspiration
to spend less money over time to live than people who have to scramble from month to month.

Put another way:
If a poor person can only afford the leaky $10 boots,
      and they last a year
              (and comes with wet feet from leaks),

A wealthy person can buy the $50 boots that last 10 years.

The poor person will have spent twice as much as the wealthy person at $100
and still have wet feet!

So now that we've decided we'd rather have dry warm feet at half the price, consider how to pay for toasty toes:
  • Theres Rate of Return for this investment to consider.
  • There are Solar Renewable Energy Certificates (SRECs) that can actually pay YOU money ! (see below)

  • There are various tax credits and other benefits at the DSIR database.

  • There are EEMs, "Energy Efficient Mortgages"
  • Federal Conservation Tax Credits.
    • On Tuesday, February 21, 2006 the Treasury Department and the Internal Revenue Service (IRS) released the long-awaited "Guidance Notices" on claiming tax incentives for energy efficiency improvements to existing homes, new energy efficient home construction and new energy efficient manufactured housing.
    • Federal home energy efficiency improvement tax breaks for home upgrades. For more information, click here.
  • The risk that your house or building will burn down without insurance is a lot less than  a stock market meltdown. What is that Peace Of Mind worth that you might be able to afford toasty toes in your retirement even with less money than you originally planned on.
  • And future inflation becomes your friend with efficiency improvements! 
    • The sun will not burn out for many generations and is free.
    • The heat coming from the earth (geothermal) is free.
    • This solar and geothermal heat you manage with insulation, airsealing, properly treated window efficiencies and other building shell efficiencies will cost you less and less as a proportion of your other expenses and income over time with inflation.

    What is it worth to have more freedom from Energy Insecurity and all the trouble that addiction to energy has gotten us into?
More from RESNET on Home Energy Mortgages

An example webpage of an Energy Efficient Mortgage (EEM) at myEnergyLoan *

*Please note that Commonwealth Solar does not recommend any particular loan products. This is only an example.


See "Roof Flashing"

Hydro Stove about to get Fresh Air Vent installed

Fresh Air Vent

Any device that consumes oxygen while burning a fuel (combustion), such as a wood stove or the gas water heater will suck conditioned air out of your living space and flush that conditioned air out the chimney or exhaust.

That is, unless you give your combustion device a "fresh air vent".
That fresh air vent gives your combustion devices (gas, oil or wood fired boilers, gas or oil hot water heaters, fireplaces) a place to get fresh air besides your air.

Another benefit is that your house doesn't dry so dramatically and your skin thus is not as dried out and not as likely to get nosebleeds from overly dry air. As the combustion device sucks up air for the burning of the fuel, it tpumps that moisture laden air out its exhaust or smokestack. This creates a vacuum in the house so you feel any leaks all the more dramatically . The cold air outside is drier than the warm inside air and so the overall humidity in your house drops thus drying out your skin and nose. Flaking breaking skin and nosebleeds often result.

A fresh air vent can also make a dramatic difference to your lung's health. There are various events and conditions (such as "stack effect" caused by air leaks into the attic) that can cause a lower air pressure in your basement than the smokestack of your combustion device ... and pulls the polluted exhaust into your living space ! The fresh air vent prevents that "backdrafting" that can sometimes kill you with pollution.

In this picture, you can see a "hydrostove" with a fresh air vent installation. In this picture the vent installation is not complete so you can see part of the vent ductwork laying on the floor for you to see. Even without the stove running, you could literally see the dust on the floor blow away from the open end from the air coming in from outside! The hydrostove helps make the wood burning more effective as well since excess heat at any one time is stored by the water tank. The hydrostove makes up for hot water not heated by the occasional multiple-day overcast event that reduced the solar panel effectiveness.

Heat pump hot water heaters

Heat pump hot water heaters make more sense than solar panels if there is very little hot water used, (less than 60 gallons a day used) such as an administrative office building one or two adults in a household with no jacuzzi.
For an analysis of heat pump hot water heaters, see this Washington State University study.

As a bonus, the heat pump hot water heater can:
  • Dehumidify your space, especially useful in crawl spaces and basements, kitchens and bathrooms.
  • Add air conditioning to an adjacent space, like a kitchen or bathroom (vent the Hot Pump Hot Water Heater to that space in the warmer months, but switch to ducting to the outside in the Winter)

For more information about a system we commonly use, see:

Heat Transfer

Understanding some basics of heat transfer will help you save money and energy consumption.
  • Heat moves from a hot place to a cold place
  • Heat moves in proportion to the DIFFERENCE in temperature. So it costs more to heat a house on a 20 degree day because the heat moves more quickly out of your house.
  • Heat moves in three different ways that must be addressed differently
    • ConVECTion (with moving air) This is the most common way you lose heat (Ex: Hot air coming out of the duct leaks). Also a way to get hot air coming in during the summer.
    • ConDUCTtion (ex: The hot frying pan to your food)
    • Radiant (ex: The Sun shining on you and your house)
Any plan for efficiency, energy conservation and targeted alternative power must take all three forms of heat transfer into account.

Homeowner Association Restrictions On Solar (Deed Restrictions)

Suburban developer created deed restrictions against solar panels and certain efficiency improvements can deny people the chance to earn SRECS money for their systems and destroys people's income and freedom from energy independence.

Most Homeowner Associations (HA) are actually formed by the developer and not the homeowners. Some HA's are so restrictive as to consider flags, growing food or clothes lines as "eyesores"!! If you are unlucky enough to be stuck with such a HOA, there is hope.
Luckily satellite dishes are now exempt from those restrictions and so there is hope for sanity yet.


The theory behind insulation is to slow heat transfer. This works regardless of the direction of the heat flow. Heat moves from hot to cold places in proportion to the difference in temperature. So in summer, your air conditioned house loses heat outward to the hot outside. Your house will get hot faster when its hotter outside. In the Winter, reverse the process. Insulation will work the same in either case.

Insulation slows heat transfer by impeding the three different way that heat moves (see heat transfer)
The most effective insulation is a vacuum. That is why we used to have "vaccuum thermos" containers before we came up with advanced closed cell foam that could be blown into shapes.
In a vaccuum, the heat cannot move by either convection or conduction.

The next most effective insulation is air. STILL air. If the air moves either through an area, then it is transferring the heat by convection, like in your oven. Air gaps that are too large can have "convection currents" that go in a loop to carry the heat from a cooler window pane to a hotter one. Or inside a wall gap. If there is a leak, then the air just carries the heat with it through the air gap. That is why leaks are so important to heat loss control.

So the goal is if you can't have a vacuum, to keep the air STILL. That is why double paned windows and foam and air barriers with fiberglass work better than single pane windows or fiberglass with no air barrier.
Fiberglass is used on engine air filters. Fiberglass does not stop air flow. So without an air barrier, fiberglass is nearly worthless, only slowing the heat loss slightly.

Closed cell foam works by trapping cells of air. Open cell foam also traps some air, but not as much. Styrofoam encapsulates tiny tiny air bubbles in plastic.
Storm windows work by slowing or stopping air flow.
Cellular shades work by trapping a cell of air.
Exterior insulation works by trapping air outside stone and mortar so the air inside can use the stone as a "thermal battery" and store heat.

Eventually entropy wins and everything ends up the same temperature. Insulation only slows that process down.

Interior Storm Windows

Interior storm windows are very easily made of "clear" pine or other more attractive wood and slips into the inside of the window to create an air barrier for far less than a new replacement window. It also allows you to keep the historic windows but stop the air loss.
Also interior storms can be constructed for rental historic office or residences cheaply enough to save more than what was spent on the storm windows. There are also more permanently attached magnetic interior storm windows.

Interior storm windows stop the air leakage that accounts for MOST of the lost heating or air conditioning. Then shade cloth in the summer prevents too much radiant heat from the sun coming in. Cell Shades are like instant retractible insulation for your windows
Cellular shades can insulate the windows from conducted heat lost in both winter (nighttime) and the summer (daytime).

Generally interior storm windows are made on a wooden frame sized to the window minus about 1/8th of an inch. Then weatherstripping is applied to the outside after PolyOlefin ("heat shrink") film is wrapped around that frame. That weatherstripping provides both the air seal and the friction to keep the interior storm window in place.

Commonwealth Solar can manufacture interior storm windows.

Interior Storm Window is a cherry frame with Poly Olefin (heat shrink) film wrapped around it

Incandescent Lights are mostly resistant strip heaters


Illumination makes up a huge part of any typical energy bill for a building.
There are several issues that can be addressed to make lighting more beautiful and efficient

  • Incandescent lights are essentially heaters that also make light since 90% of the energy goes into making heat. There are other ways to illuminate your work and play space.
    • The worst problem case are the recessed incandescent lights or halogens that are each a potential fire hazard and "smoke stack" that will pull heated or cooled air right out of your living space! Recessed Lights are MAJOR leak point!

      A professional energy auditor will pay a lot of attention to recessed lighting.

      Many times there is no insulation or sealing on the recessed lighting containers and this becomes the equivalent of several wide-open windows!!!

  • Fluorescent lights are now available in may colors of light, not just "flickering blue".
  • "Light Tubes" can bring in light from the sun through your roof yet are air sealed and insulated unlike skylights.
  • LED (Light Emitting Diode) lights are in rapid development and can provide solar powered backup task lighting for your dark corners or key places like bathroom, kitchen countertops etc. and can provide a lower cost way to have emergency lighting backup than building a solar panel system to run the entire house.

Misconceptions that Misappropriate your Money

There are many common misconceptions and occasionally misinformation  that will waste your money and give you very little to no comfort increase for the dollar.
Once you understand some basics, you can see where a trained energy detective auditor can make a huge difference for much less investment.

Here's just a selection of four examples:

Example 1: Fiberglass insulation. Air filters are often made of fiberglass. You can often SEE where a leak of air has passed THROUGH the fiberglass insulation by the dirt that it has filtered out of the passing air.

Fiberglass insulation only works when there is no air flow or air pressure. Typically an air barrier of some kind ensures no airflow so that the insulation can work.

Dusty dirty fiberglass tells you that either
    no air barrier was installed,
         or was badly installed,
                or has failed.

Using blown celluloses insulation instead of rolls of ineffective fiberglass does a much better job of filling in gaps and stopping air flow.
Commonwealth Solar provides the service of blowing cellulose insulation  and simultaneously sealing your attic and walls after a proper audit

For more information on controlling air flow with insulation and vapor barriers see Building

foil bubble insulation can reflect heat back toward YOU
Example 2: Misconception: Radiators are inefficient. A radiator will lose the most heat to whatever is closest and coldest. Heat goes from a hot place to a cold place.
So what is the coldest place that is closest to your radiators?
The wall of course!

So by placing pennies worth of reflective foam insulation behind your radiator you dramatically lessen the lost heat to that cold exterior wall!

Example 3: Solar Attic Fans. An attic stays hot long after the sun goes down. Also the purpose of ventilation is to remove moisture (if there is any) as well. A solar activated fan typically does NOT have any moisture sensor.

Far better to
  • install a ridge vent and/or
  • bury your ductwork in blown cellulose insulation and/or either
  • get a reflective roof such as TPO with insulation under the membrane or
    • seal the roof in something like the silver or white coating that also has the benefit of protecting your roof tiles, metal or membrane from the sun's UV and heat.
    • This will also reduce the heat load on whatever is inside your attic, such as your heat pump air-handler. The less your air handler has to fight, the less you pay and the longer it lasts.
Example 4: "Houses must breathe". A house must stay dry. You do the breathing. Properly handling the moisture is the key. A musty smell and dripping windows are your hints that there is a problem. Building Performance Institute literally wrote the DOE book on moisture management health issues from mold.

[More on energy wasted by ductwork
in the attic and how you can save that]

More On why a Professional Energy Audit
should always be a part of
purchasing or upgrading a house.

There are many other misconceptions for which there are tricks of the trade.
Call Commonwealth Solar to have an energy detective find your energy thieves and help you spend the money you already use for energy much more effectively!


A house does not need to "breathe".
A house needs to stay DRY to prevent rotting, rusting and mold that harms you and the house.

Moisture can come from uncovered earth beneath the house in the crawl space or through untreated concrete in a basement or leaks from above in the roof or walls or window frames or from plumbing or improperly plumbed equipment such as the air conditioner handler.

Moisture is mostly carried on air currents. That's why kitchens and bathrooms come with powered vents to remove excess moisture after bathing and cooking.
So by stopping air flow with proper air sealing and insulation to prevent condensation is the most effective way to prevent transfer of moisture.

Moisture above 49% humidity can cause ubiquitous mold spores to grow and damage wood and in some cases, people's lungs etc.

You can never "eliminate" mold. Mold is ubiquitous in nature and is ever-present.

You can only control mold by denying the spores access to moisture or organic materials that give a great base to grow on.

One way to control mold during a building upgrade is to use "paperless sheetrock" that uses fiberglass matting instead of paper to contain the gypsum. While plaster itself is not very friendly to mold, the wooden lathwork that is typically used with plaster is VERY mold friendly.

For more detailed information on moisture and its control visit Building
Building Science literally wrote the Department of Energy books on moisture control and "sick building syndrome".


Phase coined by Amory and Hunter Lovins of the Rocky Mountain Institute in a book titled, Brittle Power: Energy Strategy for National Security  (pdf) in 1982 .
The idea is that for several reasons, a saved watt can be more effective than another watt of produced energy. Some selected reasons (not limited to) :
  • Energy from a centralized huge remote coal, nuclear or hydro power station is lost in the high voltage transmission lines. If you have a more efficient device that used one less watt, its actually the same as MORE than one watt of greater production needed for the less efficient device!
  • Centralized systems are subject to brownouts when consumption exceeds the systems ability to maintain voltage levels. More efficient devices and buildings means less brownouts. Sometimes brownouts lead to blackouts.
  • More energy production leaves massive pollution behind. Less pollution and destruction of nature means more of a legacy for children to come.
  • Since we have not yet learned how to harvest materials from asteroids, the moon or other planets, we currently only have ONE planet of materials. Its prudent to consider "Waste Not Want Not".
  • If your systems are very efficient, they can often run off batteries charged with solar power much more cost-effectively thus giving you freedom and peace of mind as well as health, wealth and wisdom (since now you have the time to reflect instead of rushing from job to job frantically to pay for more production).
  • DONT FORGET THE WASTE IN THE TRANSMISSION LINES  And if you are no longer beholden to centralized power brokers, you are freer to be who you want to be.

Passive Solar

Passive solar are architectural features that do not require your active participation in order to manage the energy from the sun as it impacts your house.
For example,  careful placement of windows can allow the sun to heat your entire house even when there is snow on the ground!

While most passive solar features must be considered at the time of design for the building or addition, there are some features that can be retrofitted later.
For example, proper placement of appropriate trees can dramatically increase solar gain in the winter while reducing the solar impact in the summer.

Related to "Passive Solar" is the concept of "Passive Survivability" ...

Passive Survivability

Passive Survivability is an architectural concept that can make an "off the grid" or emergency backup energy system much more affordable as well as protect the occupants in emergencies.

One way to use Passive Survivability to make an emergency system more affortdable:
  • Make a list of the functions of your building that make it useful.
  • Then put power or resource requirements to each those functions.
  • Now rank the importance of those building functions like "flat place to sleep that isn't frozen", or "non frozen water pipes" or "medicines like insulin kept cold in August".
  • Now you create efficiencies that make those functions less difficult to sustain ...
  • And finally plan for alternative energy systems to feed only those functions that are absolutely necessary during emergencies.

Another way an electrician might think of Passive Survivability when wiring up Solar PhotoVoltaic panels to provide electrical power from the sun is to talk in terms of a "Dedicated Loads Panel" that puts the solar power into a selection of the breakers for your house such as the microwave, refrigerator and water pump, lighting just for the halls, bathroom and kitchen.

This means you only power the vital functions making the system that much more cost-effective.

Further Reading:

Pellet Stoves

Pellet stoves use wood waste that has been formed into pellets. Those pellets are loaded into a hopper that is loaded by a computer controlled wood stove at just the rate that results in the cleanest burn for just the amount of heat needed at that moment. This is an improvement over a regular wood stove that requires large-ish logs to be cut up appropriately and then manually stuffed into the stove and lit. The pellet stove can start up on a timer and avoids all the mess of manually cut up wood and ashes as well as potential fire hazards from manually cut and loaded wood if not handled carefully.

A wood burning stove can be an effective way to take the morning chill off without running up your electric bill with the heat pump.
Heat pumps are less efficient for heating as the outdoor temperature drops.
So since it is coldest in the morning just before the dawn, a pellet stove on a timer or as auxiliary heat on a smart programmable thermostat could kick on at 5am or so and warm the house at less cost than a heat pump. Then the heat pump could come on in the afternoon just before you get home to take that afternoon heat and sunlight and "charge" the house with extra warmth (say up to 70 degrees) for your return from work or school!

Farmers could support the electric grid by installing solar panels that will actually be the most efficient in the cool of a clear morning, but using pellet stoves to heat the bedroom and bathroom and sell that excess energy for lighting and the shower.

Pellet stoves can use a renewable Virginia resource to heat with very little electrical power (just for the fan and auger to move the pellets.)


Pests like mice, rats, crickets, spiders etc. need moisture, food and shelter to survive. Deny pests any or all and they leave your house or die.

Sealing a house against air leaks closes off many routes to moisture, food and shelter that pests need to survive.
One of the best ways to control cockroaches is to caulk the baseboards.

Termites like crickets must have ready access to lots of moisture. You can tell a house has a moisture issue by how large a cloud of crickets greets you in the crawl space or basement. Dont worry if a few hundred bounce off you, they don't bite. Crickets are just an indicator of far more insidiously damaging moisture problems.

Spiders like to eat flying insects so they set up their webs in the air flow.
Spiders are a hint that air may be leaking in or out behind that spider web.

And while a mouse can fit through anything their heads fit through, if you stop air molecules, its doubtful a mouse will get through either! Don't forget that mice will climb up the outside of a house and come down in through the attic! This is another reason that it is important to seal penetration points into the attic as well as insulate.

Programmable Thermostats

A programmable thermostat can really help you be comfortable for less.

Programmable Thermostats help the most with heat pumps as opposed to electric strip, oil or gas fired furnaces or boilers. However, a good quality programmable thermostat can incorporate those features.

Since air leaks ensure that whatever air you heated or cooled 8 hours ago has long since leaked out and headed downwind of your house or up into the clouds ... a programmable thermostat cuts back the effort of your heat pump, furnace or Air Conditioner when you are not around.
Now, that said, there are some additional factors to keep in mind!
  • Thermal Mass. If your living space is right up against a really thick wall or floor, it will take HOURS to heat up or cool that down. In which case a nighttime set-back may make little difference.
    This is obviously a site-specific problem. A thorough energy audit can analyze this for you. Thick walls or other features can act as "Thermal shock absorbers and slow the rise and fall of temperatures in your building.
  • If you have a heat pump, make sure that the thermostat locks out the auxiliary electric strip heat based upon the outside temperature.
  • Not all "programmable" thermostats have an intelligent recovery feature that reduces overuse of the electric strip. The intelligent recovery times the system to slowly (and more efficiently) bring the temperature to the desired point at the programmed time instead of just coming on full force at the time programmed into thermostats that lack intelligent recovery.
  • Heating more in the day or cooling more at night can "Charge" your building's "thermal batteries" if :
    • You are using an air-source heat pump (this strategy does not work for electric strip, oil or gas fired furnaces)
      (Air Source heat pumps are more efficiently heating on Winter days
      and running the AC at night in the Summer)
    • There is a thermal mass to "store" that temperature. Like an older brck house where the bricks are structural and a foot or more thick. So this trick does not work as well on a house that has a wood frame or where the insulation isolates the bricks from your heating system.
      If your bricks are insulated on the outside, then you get a bonus! Your system will now heat and cool against the average outside temperature instead of whatever temperature it is today. This makes a kind of "thermal shock absorber" that your system can more efficiently work with.
  • In the summer, you can set some thermostats to activate on humidity instead of temperatures. Since people sweat to cool off, the humidity makes more difference to comfort than the actual temperature. Also humidity is more important to mold and mildew control than temperature. A humidistat option can save you a lot of money!
Make sure you install the programmable thermostat that fits the configuration of your house! Thermostats for heat pumps are different than thermostats for electric strip, oil or gas fired furnaces.

A professional energy audit can help here.

Energy Star on Programmable Thermostats

Radiant Floor Heating (with solar energy)

Thermal Solar panels are most efficient the lower the needed output temperature.
Since a hot transfer coil in a forced-air heat ducted system needs at least 130 degrees F to 180 degrees F ... trying to use solar thermal panels for space heating is quite challenging.

Unless your space heating only needs 80 to 100 degrees F for the working fluid to transfer heat!

A radiant floor heat system that uses 80 degree to 100 degree water in tubes under your feet is easily achieved with solar thermal panels!

According to This Old House, for example, a radiant system can be up to 30 percent more efficient than forced-air heating, depending on how well insulated a house is.

Tool Base on Radiant Floor Heating .
Commonwealth Solar offices have floor heated by solar panels! Call to come by and see it in action! The floor will often be over 60 degrees F even when its below freezing outside.

Rate of Return on investment in conservation and solar energy systems.

While all investments pose some degree of risk, the return on a solar energy system is about as safe and predictable as, well, the rising sun. Since the equipment is insured, this investment is as risk free as it can get!

Also consider that if we are lucky, we all eventually come to a point where we will live on a fixed income. Wouldn't it be good if the COST OF OUR FUEL WAS ALSO FIXED or even available?

Peak Oil will eventually mean that new easily accessible oil and natural gas will no longer be easily pumped out of the ground and that means that scarecity and high prices are guaranteed at some unknown time in the future. Since China and India are dramatically increasing their consumption of oil and natural gas, that is very likely sooner than later!

Don't forget that coal and uranium use oil in the extraction and transport processes.

And, after all, even if the US Government fell, you house will probably still be standing. And your building or house (unlike your 401k) was insured, right?

So while solar fuel is free, the equipment to collect, store and deliver it is not.
Conservation is very cost effective, though again, not free.
So what is the rate of return on investment on conservation and solar energy verses other investments, most of which are taxed ?

The US Department of Energy estimates that over 5.6 million homes have been weatherized, saving 30.5 million MBtu of energy each year. DOE estimates weatherization returns $2.69 for each dollar spent on the program, realized in energy and non-energy benefits. Families whose homes are weatherized are expected to save $358 on their first year's utility bills.[2]

Making the upgrades for Energy Star certification costs just 1 to 3 percent more but pays for itself immediately.  According to Energy Star, Energy Star House upgrades (such as windows with reduced air leakage, properly sealed and insulated ductwork, insulated attics etc.)add just $10 to $15 per month to your mortgage payment but save you around $25 to $45 per month on your utility bills. 

Many state LIHEAP (Low Income Home Energy Assistance) programs work side by side with US Weatherization Assistance Program (WAP) to provide both immediate and long term solutions to energy poverty.

Other Examples:

Commonwealth Solar Example:
If a $6000 solar thermal system was installed for a 4 person household:
Solar Thermal can typically reduce hot water electric (or gas) heating between 75% and 80%.

A typical household will use 20 gallons per person with a 70 degree rise in the hot water tank,
according to ASHREA (American Society of Heating, Refrigerating and Air-Conditioning Engineers) figures used for standards to plan by for Architects,

8.33 btu/gallon
20 gallons per day in a 4 person household is 80 gallons a day.
70 degrees increse (from typical 50 degree cold water to 120 degree storage temp)
That is 46,648 btu / day for that household.

3413 btu/Kilowatt Hour
12 cents per KwHr (divide your electric bill including everything for what you REALLY pay!) Typically as of March 2009, most people find that by dividing their monthly total payment by the number of kilowatt hours used for that period, that they pay about 12 cents per KwHr.
13.6 KwHrs is $1.60 per day.
$584/ year for a regular electric resistive strip hot water heater.

And a typical two panel system for a family of four saves 80% off the resistive tank so that SAVES $467.20

So now apply that SIMPLIFIED Rate of Return formula:
$467.20 / $6000 * 100 = 7.786% Investment Rate of Return
    NOT including fuel surcharge increases !   (energy inflation)
       Keep in mind that China and India are dramatically increasing their energy usage ...
    NOT including Tax Credits
    NOT including SRECS (sends YOU money !)

Those last three items are moving targets and are hard to impossible to calculate!
So consider that almost 8% as GURANTEED MINIMUM by quite a long shot!
And its insured by your homeowner insurance. Was your 401K insured?

The system can last 30 years easily so ... what's that investment worth after 30 years?
That investment is the equivalent in $63,309 after 30 years when you have to rehab the system or install a new one. Sometimes they last longer! Commonwealth Solar has been installing systems since 1975 and many are still in operation!

ALSO ... that's $63,309 that was NOT TAXED!
That's an additional $63,309 that was not taxed that you can invest for retirement, use to go back to college, send your kids to college ... start a business.

The payments for an Energy Efficient Mortgage at some 7% or sometimes lower is way less than the savings from the energy efficiency investment. And then you pay it off and still keep the savings!

Speaking of keeping the savings - small savings can really get you out from under that mortgage a lot earlier! Freedom From Debt Much Sooner! In this example, if you saved $43/mo you could pay off your mortgage three years earlier.

And finally, what is the rate of return on safely reducing your utility bills many decades into the future when your income may be less than it is now? What is the investment value of Peace Of Mind and Freedom to live on less when you are older and living on a fixed income that may not be as high as you originally planned?

[Sample Analysis for example]

Resistive Strip Heat Sources

THE most wasteful way to heat anything with electricity is a strip of wire.
Its referred to as a "resistive strip" though often it is in a coil form.

In most heat pumps it is often called "auxiliary" heat or "emergency" heat. It is often kicked on when the thermostat is run up more than 2 degrees from the current temperature. So be careful what kind of thermostat you use and how it operates that resistive strip. Some heat pumps use gas or hot water as the backup in which case this does not apply.

The exception is when you need heat in short blasts for little capitol envestment and then save a lot of energy because the rest of the space is less or not heated.

An example would be a heater pad for your dog or feet where you sit so the dog or feet are heated directly and the rest of the house is left at 62 degrees. Another example is a radiant heater in a bathroom. You only heat your body directly as you come out of the shower with a focused parabolic shaped heater with the glowing strip in the center. That way you leave the air temperatures low during the other 23 hours and only heat your body as you exit the shower. Don't forget to put those on a temperature sensor (so a warm sunny day cuts off the foot warmer or dogwarmer) or timer or have the memory of an elephant.

Speaking of hot water, the most common place to find a resistive strip is in an electric hot water heater.
This is why anything you can do to reduce that heat use will save you relatively large amounts of money.
Insulate the pipes coming out of the tank (don't forget the emergency  overpressure valve! Leave a little gap for the water to escape in emergency from that valve)

This is why thermal solar hot water is often a very cost effective investment and why for smaller households that use little hot water, a heat pump water heater is cost-effective. You also get a bonus of dehumidification and cooling of wherever that heat pump hot water heater is.

So watch out for any claims that so-and-so heater will save you money ... does it have any variation of a resistive strip? It might be more efficient if you only heat very small spaces for short periods of time - like the bathroom or the doghouse.
  • An incandescent lightbulb "heat lamp" is a resistant strip.  Even if they put it in a box!
  • Electric baseboard heaters are resistant strips.
  • Those portable oil filled radiators use resistant strips.
  • The "Auxiliary" or "Emergency Heat" on some heat pumps are resistant strips
  • Infrared heaters usually use resistant strips


Radon is a radioactive gas that is emitted by Granite.
Proper sealing of a basement or crawl space should vent the radon.

Roof Coating

Silver or White coating can be painted on the roof shingles or membrane to increase its reflection of the Infrared Light ("heat") from the sun reducing peak cooling time costs by 10 to 15% (Energy Star) to 40% (Heat Island Group) . Please note there is a recommended technique to applying this material correctly.
When choosing a coating Pay attention to the "emissivity" of the coating, shingles or membrane.

ALSO silver rarely allows the black staining from the mold and mildew that often grows on asphalt roof tiles. Thus it will likely actually look better than the bare roofing shingles.

And ALSO the Silver or White reflective roof coating will protect the roofing shingles and membranes so that you get much more lifespan out of the roof

And finally, whatever is in the attic (such as the air handler for the air-conditioning heat pump) will suffer less heat as well as the ductwork thus reducing your air-conditioning bill!

One of the Commonwealth Solar installers, Christopher Maxwell, put a TPO Energy Star reflective membrane on his 1906 downtown style brick urban row house with a with passive vented attic. The summer temperatures that occasionally hit 103 degrees F in the shade of a roadside tree correlated with about a 95 degree attic at the same time. The second floor was 92 and the first floor was 88 degrees F with no air conditioning at that time! It was possible to use that space for storage of most anything after applying the reflective roofing. Also not so bad to work in when needed

Roof Flashing

Many solar panel installers do not give consideration to future roofing repair and maintenance.
After 35 years of experience, we've had to go back and remove panels so a roof can have its shingles or membrane replaced. Now we put flashing on our panels and racks so that roofers can just replace the roof membranes and shingles around the panels without disturbing them. The panels protect the roof underneath them.
The flashing is also angled with a downward slope so that snow and leaves dont end up trapped on top and can fall away. This also helps preserve the roof.
Solar Panel with flashing to enable roof shingle maintenance and replacement without disturbing the solar panel

Here's another reason we flash the solar panels:

Photo showing snow on top of panel before we installed flashing. Leaves would also cause damage to the roof if allowed to be trapped behind the solar panelSnow and leaves should not be allowed to get backed up behind the panel and rot the roof. This photo shows the installation on the Davis house before we added the  flashing. The pipe is shown insulated all the way, of course. The  flashing  is installed with a slight positive slope so that leaves and snow don't back up behind a "dam" of flashing either and flows off for cleanup.

Shade Cloth is used to reduce heat load in hotter months for sensitive plants in greenhouses

Shade Cloth

Shade Cloth is typically used by greenhouses to cheaply reduce over-heating in the summer.
It can work wonders for your house or building just as well !
It is
  • far more effective than architectural overhangs
  • and reduces glare yet still can be seen through, unlike shutters.
  • reduces fading of furniture and rugs
  • The heat is absorbed and reflected OUTside of your living space thus stopping the excess heat before it comes in your windows!
  • Best of all, in the winter, it can be retracted or removed to let that solar gain in through the window to heat your house for free!
Shade Cloth can reduce heat in your house just as well as a greenhouse by intercepting the sunlight BEFORE it comes in your window

The sun coming in each of your plain windows can bring in almost as much heat as an electric space heater per window! So the shade cloth can really make life much calmer, cooler and easier on your air-conditioner and thus your sweaty armpits and wallet.

Commonwealth Solar can consult on and install all the various forms of window insulation and heat control including shade cloth.


Shading is a very important issue for solar panels.
Solar panels are like many sun-loving flowering plants, they MUST have DIRECT sun and the panels must FACE the sunlight in order to work well. Solar panels are also most effective when tilted at an angle (inclination) equal to the latitude on the Earth. In central Virginia that is about 37 or 38 degrees inclined from the ground (horizon).
Notice for example that few plants besides moss grown on walls? That's why.

Its amazing how many solar panels are placed or maintained without this consideration.

Shading affects photovoltaic (electricity generating) panels much more dramatically than solar thermal panels.
A solar thermal panel can have a small percentage of the panel shaded by, say, a large branch of a tree or corner of a chimney.

But solar photovoltaic (PV, the electicity generating cells) must have UNinturrupted solar along a "string" of panels.

An excellent example you are more likely to be experienced with are Christmas lights whose bulbs have been wired in series so that one bulb goes out and the entire string stops working.
Solar PV cells are the same way. When a panel is wired in series (as they almost always are since each cell only produces half a volt and we need from 48 to 120 or even 600 volts for a fully effective solar installation) with two or more panels, shade that is completely covering any ONE of those cells will inturrupt the electicity for the whole string. Now sometimes you will see a pair or more strings that are wired in parrallel. The shading only knocks out the one string that is shaded, cutting the power of that system by one third (in a three string system). But if that shade from a chimney or tree branch cuts one cell in EACH string completely, then the whole system is out.

So when considering location for solar, remember that for PV, no single one cell can be completely covered by shading or the whole panel and string attached to that panel are now out.

Again, Solar Thermal is not as affected, but shading is important to full performance there as well.

Watch your trees! They will grow. Check the species you have and what their mature height and spread will be. Trees near your house are good for cooling your house (use Gutter Helmets or similar to keep your rain gutters clear) so you might consider putting your solar panels on an "out building" like a tool shed or carport.

Solar Gain

The sun will generally transfer 200 btu/square foot through a clear panel of glass.
A typical window thus transfers almost as much heat as a typical 1500 watt space heaters!
Straight clear sun is over 300 btu. Clear glass is about 80% clear to sunlight.
A typical window 3x5 feet so that's 15 square feet = 3000 btu
1 KW is 3400 btus   space heater is typically 5000 btu

So you want to use that gain to heat your home in the winter, and get rid of that heat in the summer with exterior shade cloth


Solar Renewable Energy Certificates (or “Credits”) (SRECs) are a commodity traded in the USA that represent 1 megawatt hour of energy supplied to the electrical grid using “Net Metering”.

You could get a quarterly check for your installed solar generation system!

Sol Systems LLC, a commodity brokerage, states that their anticipated 5 year average SREC price is $350 on their Virginia Pricing web page. The value of the SREC is paid quarterly to the system owner after subtracting the brokerage fee.

SRECs came into existence when states implemented an RPS (Renewable Portfolio Standards) in response to citizen demand for stable, sustainable power that polluted less.

NREL map of SRECS updated from Union of Concerned Scientists in 2007

An RPS requires certain percentages (a Portfolio) of a region's power supplied comes from Renewable Energy sources. Virginia is a part of the region called the PJM power pool for DC, MD, PA etc. 

Many states near Virginia connected to the PJM power pool have mandatory RPSs that are enforced with a NonCompliance Fee (NCF) also known as an Alternative Compliance Payment (ACP). Some states such as Virginia have a voluntary RPS (‘goal’).

A large power producer such as Dominion or power consumer may purchase SRECS so they can legitimately claim to have met the standard percentage or goal required of their power from solar energy without actually mounting a system on their building or land. Purchasing SRECs for a system on your building helps Dominion etc. avoid the controversy associated with running more power lines from centralized systems hundreds of miles away.
Projected Growth of SRECS

   1000kWh = 1 REC.

Volatility in the price of traditional energy sources due to both greater demand by China and India as well as manipulation for economic or political gains by energy players also pushes the implementation of RPSs and the resulting SREC commodity market. Fear of future shortages is bolstered by the fact that even traditionally conservative energy producers such as T. Boone Pickens now sees a decline, known as Peak Oil, in the efficiency of extraction for uranium, oil or coal. 

In contrast, the sun is a stable source of energy that cannot be manipulated by large corporate or political forces. 

SRECs are a commodity whose price depends on supply and demand. The value is provided by an NCF or ACP set by the government body demanding that the utility providing power to their citizens meet the RPS. This creates a modicum of a guranteed market for stable investment. On the demand side, often companies or government agencies buy SRECs also sometimes known as “Green Tags”.

Wikipedia reports, The Air Force is the largest purchaser in the US government in absolute terms, purchasing 899,142 MWH worth of RECs. Among colleges and universities, the University of Pennsylvania in Philadelphia is the largest purchaser of RECs, buying 192,727 MWH of RECs from wind power. The corporate leader is Intel, with 1,302,040 MWH purchased in 2007, and the largest purchaser among retailers is Whole Foods, which purchased 509,104 MWH, or enough RECs to offset 100% of its electricity needs.

Dominion sells an option to their subscribers for renewably produced energy at $2 per 133kwhrs.
The $2 blocks translates to $15 per REC. Please note the lack of an ‘S’, these are largely not solar credits!
Dominion’s low price for voluntary RECs (mostly wind power) shows the value of mandatory RECs that is predominant in most states at different rates. The $2 rate may be a bit misleading since wind power is not limitless. Wind power is limited by the availability of suitable sites with enough steadily available wind and by opposition from citizens and by the corrosion and lightning damage to marine wind turbines that leads to high maintenance costs. Solar power on the other hand can be placed in any sunny space such as your roof, as shading on a parking deck or the roof of a mall.

SREC commodity trading is complicated by dozens of states with different RPSs and NCFs or ACPs so finding the spot value of an SREC can be challenging. A further complication - states with voluntary RPS or goals have no enforced NCF or ACP. This complication explains the existence of brokers of SRECs such as Sol Systems LLC. Commonwealth Solar LLC has negotiated a contract with Sol Systems aiming for as realistic a balance to ensure working systems as possible at this time. For example, following consultation with Commonwealth Solar LLC., Sol Systems has now added requirements to list the equipment, model numbers and show that the system is not shaded as a control against fraudulent system claims that may come about as the shysters discover SRECs. This is one reason why Commonwealth Solar has survived through the boom and bust cycles since 1976 - a real desire for effective affordable solar energy in efficient buildings.

A further complication is that SOLAR Renewable Energy Certificates are made more valuable by different statutory provisions in different states. The method and amount differs by each state or even city that sets the Renewable Portfolio Standard (or Feed In Tariff) for power sold to their citizens. 

Another factor in the price of SRECs beyond a desire for energy prices as stable as the sun is the realization that pollution costs our citizens and economy and resulting demand for reduction of that pollution with (among other tactics) RPSs that push for creation of energy that cost us less by polluting far less. 

From Wikipedia:    (  )

‘Life-cycle analyses show that the energy intensity of typical solar photovoltaic technologies is rapidly evolving. In 2000 the energy payback time was estimated as 8 to 11 years[80], but more recent studies suggest that technological progress has reduced this to 1.5 to 3.5 years for crystalline silicon PV systems [79].’

A third factor (of many) in the price of SREC commodities is recent talk of a national RPS.

If the possible national PPS includes a reasonable mandatory NCF or ACP, then when combined with the difficulty utilities have in laying new large power lines, there will likely be an explosion in the demand for distributed power production that can be paid for with SRECs rather than centralized big utility grade systems.

Centralized utility grade alternative power out in the middle of unpopulated areas must be backfed hundreds of miles into the grid with huge power lines. In December 2008 reported that a national RPS may allow double counting of your SREC depending on how it’s written. 

RPS and SRECs can also help combat fraud and abuse of the upcoming boom in solar energy. Fraudulent and incompetently installed systems in the last boom/bust cycle trashed the solar industry for a generation harming most and only helping a few shysters.

The recent efforts toward Smart Grids could require that all systems that receive any public benefit funds or tax breaks be measured in their outputs. 

The smart grid could both measure and report which systems really worked and which worked better so the buyers, regulators, installers and maintainers of solar systems would have motivation as well as a verification method to ensure a properly functioning system. Also even the best intentioned and installed system can have breakdowns and a constant means of measuring will provide alert and diagnostic functions.

In the meantime, it is becoming more likely that anyone buying SRECs or brokering them will require some verification with a production meter attached to the solar system. 

The web page on Virginia Pricing for SRECs by Sol System LLC shows a price for $350 per SREC as their anticipated 5 year average price. The broker pays quarterly minus their usual brokerage fee. This includes the fact that Virginia has a voluntary RPS. This may change (probably for the better) with a mandatory RPS in Virginia or a national RPS.


Sources and further reading:

Sharing Capitol Ideas website:

(please note that SOLAR Renewable Energy Certificates are worth more than other energy sourced certificates.)


Sol Systems position on Carbon Trading vs Renewable Portfolio Standards

The summary: Carbon Capture of coal is vaporware and doesn’t exist – solar has existed now for many decades!


Virginia goals for Renewable Energy:


Dominion’s voluntary sale of “Green Power”


Some leading advocates of an RPS for Virginia:


   Energy And Security Group

   Energy Justice Network (critical of any RPS that allows dirty power to be counted)


Wikipedia for more detailed information:

  Buyers of “Green Tags” or RECs and SRECs:

  Comparing the different methods of providing incentives for solar energy:

  Feed In Tariffs : Originally enacted by President Jimmy Carter but  made famous by the explosion in solar energy systems installed in Europe resulting in 9% of Spain’s energy supplied by solar power, 5% in Germany and 20% of Denmarks energy supplied by windmills.

Later on we will have a spreadsheet showing the rate of return on investment you could expect based on certain assumptions with SRECs at different values. You then plug in whatever your information sources cause you to think they will be worth and inform your consideration accordingly.

Stack effect is just like a smokestack, the hot air rises in the house, drawing in cold air at the bottom and blowing it out the leaks in the attic

Stack Effect

How does the smoke get out of a chimney instead of coming into the house? Because hot air rises and creates suction at the bottom pulling the smoke up and out the top of the stack.

The same thing happens in any box ... including your house!
That is why you feel a draft at the bottom of a door more than the top. And why the basement leaks are SO obvious when you find them. But you can't seem to feel any leaks on the top floor ceilings.

That is also why the windows in the middle make less difference (in still air) than air-sealing the basement, crawl space and attic.

That is also why air leaks and infiltration is the #1 cause of lost cooling and heating.
And also why open fireplaces are a major source of lost heat ... and why they often have glass doors in front of them.

One tip that this is rampant in your building is extra-dry air leading to chalking skin and nosebleeds.
Combustion of air in your living space is then exhausted along with the moisture and the cold air coming in is relatively dry thus dramatically drying out your living space air and causing dry skin and  your nose.

TIP: CLOSE THE CHIMNEY DAMPER When its not in use!
"According to the Department of Energy, a lit fireplace sucks about 24,000 cubic feet of furnace-heated air up your chimney each hour.
Bonus: It's replaced by cold air that comes in the opposite direction through the same opening, causing your furnace to work extra hard to keep your house toasty.
Crack a window in the room where the fireplace is located and then close the door, so it doesn't suck too much warm air from the rest of the house.

TIP: Provide a "Fresh Air Vent" for your combustion devices (gas fired hot water heater, furnace, fireplace, etc.)

Stagnation damage

"Stagnation - when the pump ... does not run as intended during sunny conditions. With a closed-loop glycol system the HTF (Heat Transfer Fluid) is then left sitting in full sunshine in the solar collectors, without circulating. The fluids are heated to a point where the buffers in the e.g. an antifreeze solution are broken down, and the solution can become acidic. The pressure can build up so much that the pressure valve will open. This would safeguard the integrity of the collectors and the whole system. The antifreeze has to be changed after stagnation conditions.",
page 203, Tom Lane, Solar Hot Water Systems: Lessons Learned 1977 to Today, Energy Conservation Services, 2004

Stagnation is most common when a system is put in that is either inappropriately placed (on a building or use that does not use its full capacity, especially in the hottest summer months!) or has not been maintained and doesn't pump appropriately.

Stagnation damaged systems can usually be repaired and placed back in service, but stagnation on a maintained system or recently installed system indicates that either the designer was not informed of the actual usage patterns that result after installation (misunderstandings or perhaps a change in usage pattern post installation, say, the house was foreclosed on) or was installed inappropriately perhaps for showboating to say "look how green I am" when it was an inappropriate usage.

For example, an innapropriate use for an antifreeze thermal system would be an office building with no significant hot water usage on, say, a school administration building whose staff is on vacation in August when the system needs to be used the most to reduce stagnation.

Recommendation in this example scenario of a school admin building would be to :
  • Convert from a glycol (antifreeze) loop to a "drain back" system and/or
  • move the panel(s) to the cafeteria or the swimming pool or locker room shower area for summer school use.
  • Another fix for stagnation is to stand the panels up at an very high inclination of, say, for example, 60 degrees from the horizon.This will also have the effect of making them more effective in the Winter months when hot water is all the more appreciated.

"Drain back" systems do not suffer damage from stagnation except under very rare circumstances because of a "high limit switch" that senses when the hot water storage tank has reached a high temperature limit of, say for example, 160 degrees F when any further heating could be dangerous or damaging to systems. The high limit switch turns off the system pumps and the water drains back (hence the name "drain back system") into the holding tanks. The panels are now empty except for air and stagnation is not a problem when drained.

The orange is the Thermal Envelope" and also where insulation should usually be placed

Thermal Envelope (Shell)

The thermal envelope is that border between your inside temperature and the outside temperature.

Put another way, the thermal shell describes the part of the building that separates your occupied conditioned (heated or cooled) space from the outside. For example in the attic, your "roof" comes in TWO parts. The outside part that keeps out the water ... and the floor of the attic that separates the thermal areas. The attic is vented to the outside and the insulation airseals and insulates that from your top floor rooms.

Note that the thermal envelope is not always the same exact place as the weather (liquid) envelope.

In this picture, the orange parts are generally where you would place insulation.

An exception is that, if you can, by placing the insulation on the outside of the thermal mass (bricks) you can help make the house more efficient by using that thermal mass to even out the temperature swings. Thus your heater and Air Conditioner now works against your cliamates's AVERAGE temperature instead of that day's temperature.

Here's a link to a  great example house ...


Virginia Home Energy Rating Organization was formed in the 1990s to encourage independent intelligent energy audits of buildings.

The idea is that the cost of a house is intimately tied to what it costs to heat and air condition that house. The payments for energy for an inefficient building can easily equal a car payment! Unlike cars whose many ten$ of thou$and$ of dollar$ are typically paid off in 5 year$ ... those high energy bill$ will continue to increase for many many decade$ !

Consider asking your elected representatives to bring back some variation on VaHERO or other Home Energy Rating System (HERS program) that ties the appraisal of a house during sale to an energy rating.

There are some pilot programs that may bring us back to a HERS program such as the proposal to Pilot Test a Home Performance with ENERGY STAR Contractor Partnership in December 2008

Virginia currently is NOT one of the states with a Home Performance with Energy Star program.

[more on VaHERO and HERS at Virginia Solar Energy Association]

RESNET and their belief in HERS to make mortgages more affordable through energy conservation.


Windows are often touted as a quick way to make your house more energy efficient and comfortable.

But since air leaks are THE major way to lose heated and air conditioned air ... ASK HOW WELL DO THOSE WINDOWS SEAL OUT AIR FLOW ?

A good window will have FOUR ratings. The most often hidden or not mentioned rating for a window is how well it seals against wind and air leakage due to Stack Effect.

Bob Vila recommends you select windows with air leakage ratings of 0.3 cubic feet per minute or less.

[More On Window Ratings]
[More on Window Ratings]

If the window rating sticker fails to mention how much air it leaks, its probably not a good investment.

Air leakage - air leakage can occur through and around windows, and can have a significant impact on energy use and comfort.Air leakage at existing windows may be improved through weatherstripping and caulking. New windows are often tested for their air leakage through the window (between frame and sash). Better windows have tested air leakage rates between 0.01 and 0.06 cfm/ft of perimeter. Casement, awning, and hopper type windows tend to have lower air leakage rates than double hung or slider types due to the compression of the seal when latched closed.

Watch out for stickers with no air leakage information !!

Another issue with windows is that the South facing windows should be clear with NO "low-e" coating. This is so that you can accept the sun's free warmth in the winter!

Go ahead and put low-e (emissivity) coating on the North, East  and West windows since you will not gain much heat from the sun on those windows anyway.

Then properly manage the heat through your windows with :
Shade Cloth on the outside in the summer to bounce back the sun in August
Cell Shades to keep your heat in your building on winter evenings.

Dont forget to
  • Close the cell shades in winter evenings and summer days.
  • Open the cell shades on Winter Days.
Commonwealth Solar sells and installs Comfortext Cellular Shades with automatic options.

Wind Pressure

Most of the time you are better off focusing more money and time on the basement and attic. However if your building is exposed to a lot of high wind conditions, it may make sense to spend extra attention on exterior storm windows, interior storm windows, possible window replacement (but check their air leakage rates !!!!) and of course air sealing on the upwind and downwind sides of the building.

The orange is the Thermal Envelope" and also where insulation should usually be placed

Weatherization tips:

According to the US Departement of Energy, "on average, weatherization reduces heating bills by 32%."

  • Seal bypasses (cracks, gaps, holes), especially around doors, windows, light fixtures and outlets as well as pipes that penetrate the attic ceiling, pull-downs and attic stair openings, light fixtures, and other areas with high potential for heat loss. Use caulk, foam sealant, weather-stripping, window film, electrical receptacle gaskets, door sweeps, and other items to reduce air infiltration.

  • Install insulation in walls, floors, ceilings, and around ducts and pipes, and near the foundation and sill.

  • INSULATE THE PIPES AND VALVES coming out of the hot water heater.(especially the overpressure relief valve [leave an escape path for steam if it has to blow!])
    • and consider lowering the temperature on your heater to 120 and 125 degrees.

      Please NOTE: Wrapping extra insulation around a modern tank is not very effective now with improvements in the last 20 years.
      Additionally there are liability issues if a pilot type natural gas heater has its ventilation blocked by the blanket and/or the anti scalding warning sticker is covered. However, the "little radiators" in the form of the attached pipes and overpressure relief valve have not had the same visibility as an issue and are thus often overlooked.

  • Add a shutoff valve to your low-flow shower head so you turn off the water during soaping up. Shut off the water at your sink except when you need water for rinsing.
    • You can also get a foot-pedal to shut off the water to a sink so that a press of the foot gives you a blast of water just when you need it.

  • Seal duct work by ensuring that all ductwork is sealed at joints and intersections with duct sealer, silicone caulk, an/or foil-backed tape (not duct tape)

  • Change furnace filters every month and have all heating and cooling equipment service by a professional annually. Some filters are reusable and cleanable.
    use a countdown switch timer to limit fan use
  • Put your powered vent fans in the shower and kitchen on countdown timers. Also kitchen vents can be closed even more effectively by getting a sheet of magnetic material and slapping that over the vent opening when you are not cooking. Even though the fan is off, there is usually still some air flow naturally through those vents unless they come with a fan-activated flap or valve of some kind.

  • Use solar heating on sunny days. Open drapes/curtains on south-facing windows when it is sunny outside.  Note this works best withOUT the "low-e" windows!
    At night close the drapes to retain the heat and keeps drapes closed on windows that receive no direct sunlight.

For more weatherization tips and information:

Recommended Reading

If you have any further questions, please email and ask so that we know what we need to add to this appendix !

Contact via email

Note: Last Update 06/25/2021

CommonWealth Solar, LLC

12433 Autumn Sun Lane • Ashland VA, 23005 • (804) 216 5371