Energy Star Windows and Passive Solar Design
When I was reviewing windows that are Energy Star qualified, I saw none that had a SHGC greater than 0.40. This seems to be counter productive if you are trying to maximize passive solar design.
I am sure that there are triple paned windows that have higher SHGC than .40, but are those permissible in an Energy Star home? Does the Energy Star program need to be modified to allow for higher SHGC windows to be used in passive solar homes? The Energy Star program is a great building block in sustainability, but is hampering the effectiveness of passive solar gains (in heating climates) truly encouraging sustainability?
If I am misunderstanding something then please inform me. If my assumption is correct then please share your thoughts.
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Replies
Dylan,
This has been a problem for a long time -- not necessarily for Energy Star windows, but for the tax credit program. I wrote a blog about the problem over a year ago. Here is the link: High-Solar-Gain Glazing.
Thank you for the article link, very well said. I find it ironic and sad that Energy Star prevents well-designed, passive solar, significantly energy conserving homes from achieving Green credentials and ratings. Many of which require Energy Star rating as a precondition.
Dylan, my take for years now, is that for me, build to my own specs. If a program has a flaw, I am setting the specs. not the program.
For example water conservation. Where I build we have an over abundance of water. So I focus on energy use reduction and now am pushing the local natural materials idea.
AJ,
Even in areas that "have an abundance of water" you should still be conscious about water efficiency and water conservation. I'm sure in most of the homes in your area are connected to utility potable water sources.
Many people don’t realize how much electricity is used in water purification, distribution, and sewage treatment. In some municipalities, water treatment and distribution facilities are among the top consumers of electricity. Where are most cities getting there electricity from? Dirty energy- COAL power plants.
So by reducing household water consumption you:
save water- a valuable resource
save money on reduced water bills
save money on reduced energy consumed to heat hot water
reduce carbon emissions from electricity used in water purification, distribution, and sewage treatment
Dylan,
As far as I know... You are not required to install Energy Star labeled windows in order to get an Energy Star Label for your house.
There can never be too much fresh, pure water.
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John Brooks,
1. You're right -- you don't have to use Energy Star windows to get an Energy Star Homes label.
2. Energy Star windows for Northern states can have a high solar heat-gain coefficient, so the Energy Star windows program allows high-solar gain windows.
More info on qualifying for the Energy Star Homes label via the performance path:
http://www.energystar.gov/ia/partners/bldrs_lenders_raters/downloads/PerfPathTRK.pdf
More info on qualifying for the Energy Star Homes label via the prescriptive (BOP) path:
http://www.energystar.gov/ia/partners/bldrs_lenders_raters/downloads/Nat_BOP_Final.pdf
My assumption was incorrect. Thanks, Martin for the links. I had only been familiar with the prescriptive path via my work experience. I had somehow assumed that the performance path as well, required qualified windows. The tax credit issues are still frustrating.
No, Energy Star and passive solar are not at odds. They can be complementary approaches to achieving energy-efficient and sustainable homes.
Energy Star is a program the United States (EPA) started that sets standards for energy efficiency in buildings and products. The Energy Star label is used to identify products and buildings that meet or exceed these standards. The program aims to reduce energy consumption, lower greenhouse gas emissions, and save consumers money on energy bills.
Passive solar, on the other hand, is a design strategy that uses the natural energy from the sun to heat and cool buildings. It involves designing a building to take advantage of the sun's rays for heating in the winter and shading in the summer. Passive solar design can reduce the need for mechanical heating and cooling systems, saving energy and money.
Is that you, ChatGPT?