Asheville, North Carolina - The secret to green building is a measurable thing that could cut energy bills and corresponding emissions in half, yet nobody seems to know about it. The term "green building" seems to be everywhere. It means different things to everybody and most people seem to be getting green in the face whenever they hear about it. Still, this is an extremely important issue because like transportation and food, our shelters are energy hogs. This costs us not only on our monthly utility bills, but in health and environmental pollution.
The vast majority of the energy that our buildings use is from coal. Unlike petroleum, coal supplies are relatively plentiful and cheap, insuring that we will be able to use this dirty energy to power our inefficient buildings for a long time. This is a very dangerous thing. The burning of coal is responsible for environmental and human respiratory problems that would take volumes of books to cover. If we are going to cut these emmisions which also means cutting our electric bills we must use the secret.
The secret is not a wonderful, new technology. Its actually kind of boring. However, the secret is the most important thing to consider and it transcends the world and works in all climates and on all building sites. To cut a structure's emissions you have to look at where it is using most of its energy. Heating and cooling is responsible for half of a building's energy use. Ironically, making the inside temperature of our structures comfortable, is one of the biggest drivers of climate change outside.
So if you want to cut how much energy your home and office uses you can have the greatest effect by targeting the amount of energy that is used to space heat and/or cool. There are the fun ways to address this most important aspect of energy use. Enter RE (renewable energy). Solar, wind, micro-hydro are all awesome ways of doing it. These things cost more up front and are site limited. Geothermal heat pumps heat, cool and dehumidify (needed in humid climates) all with the same equipment and use half the energy of a traditional heat pump. These are also more expensive up front and although all these technologies work brilliantly, none of these heating and cooling systems are the secret.
Most of you have probably guessed by now that the secret must be insulation. Right? Close, but not quite. Insulation is the second most important thing when building in most climates. The secret is air. Air infiltration is the single most important factor when building a structure. Buried deep within the green building movement is this all important fundamental which receives little attention, but has the greatest effect on a building's energy use.
How can air infiltration be more important than insulation or type of heating /cooling systems? Just imagine a well heated 10 foot box on a frigid day. The walls of that box are 2 feet thick of the best insulation. However, wherever those walls come together is a two-inch crack. Even with no wind, the cold air naturally replaces the indoor air. If the interior parts of the wall are cold and the air is humid, condensation is possible which can result in mold. So eliminating air infiltration is not only important for energy efficiency, but also important for building mold resistant structures.
Compared to air infiltration, nothing else matters.
Making a structure airtight is the best way to control its energy use. I am not saying we shouldn't use insulation, or the free energy of the sun and earth to heat and cool our homes, because we should. I am saying it is most important to start with an airtight envelope. Most builders ignore this most important thing. I will even say that most green builders ignore it. We need to bring this issue to light by educating each other and insisting on air sealing our existing and new buildings.
Luckily there is an easy way of measuring the air infiltration of a home. With a blower door test, you can put a fan in a door opening and measure how much a home or building leaks. Any home that is Energy Star certified requires it. This measurement known as ACH (air change per hour) is the most important number when building a structure. If you dont know the ACH you dont know how green the home truly is.
Houses need to breathe, right? Of course we just want to control it. We want to control where it breathes and how much. Indoor air quality is always worse than outdoor air quality, and many feel that it is one of the biggest problems with todays structures. When we build airtight, indoor air quality needs to be addressed. Technology to the rescue. HRVs (Heat Recovery Ventilators) and ERV s(Energy Recovery Ventilators) bring in outdoor air and exhaust indoor air. They are common for commercial buildings and are now available for houses. They are simply fans that continually supply fresh air from outside and capture the energy from the exhausted indoor air. There is no better way to make air in a building healthy in such an energy efficient manner.
So with indoor air quality taken care of how do we build airtight? Most houses are built the same way we have built since the 1920s. Stick framing uses 2x4 or 2x6 studs to make wall and roof assemblies. There are many methods to seal the sticks but most builders dont bother. I am going to cut through a lot of explanations and say that there are many studies by building scientists that prove that no matter how one builds and seals these old school wall assemblies they will never perform as well as the newer technologies of SIPS (structural insulated panels), ICFS (insulated concrete forms) and pre-cast concrete panels.
These newer wall and roof assemblies outperform the competition in three big ways. Most importantly, air infiltration. Secondly, insulation. More specifically, continuous insulation. Continuous insulation is unbroken by studs and partitions which rob performance. Lastly these newer technologies tend to be structurally stronger than the competition.
So now you know the secret. We need to begin green building and healthy living conversations with the way we prevent air infiltration. By using air tight and continuously insulated building shells, we have a much bigger impact on the environment than almost anything else. Thats a pretty bold statement I know, but many agree.
What can you do about it?
Air seal your house. Professionals do the best job, but an educated person such as yourself can make a big difference. Question builders, architects, and developers who do not use high performance walls and roofs whenever possible. In most places, they are just as affordable, available, and easy to put together as anything else.
Spread the word. The biggest problem is ignorance. We must educate each other. Not everybody will agree, but at least we will be discussing the most important issues.
Wow! Now that we got the boring old issue of air infiltration out of the way lets talk about how we are going to heat and cool our dwellings. FUN!
