The most important cost-effective construction solution used to lower energy bills is a reduction of air-leakage. The test used to determine air tightness in a home is required in the 2009 International Residential Code, it is called a blower door test. However, there is a second compliance method, the visual inspection, that most builders in Virginia use to show compliance.
Building code specifies that “the building thermal envelope shall be durably sealed to limit infiltration.” Unfortunately the visual inspection provision weakens this requirement to a point that it makes no impact on most homes being constructed. The blower door is the only effective way to determine total air leakage and verify the home is as air tight as required by the building code (the worst possible construction allowed by law).
A blower door test is used to determine total air leakage of a home’s thermal envelope. The powerful fan is installed in an exterior door and the house is depressurized. The result is a measure of the home’s air tightness. This test simulates the air leakage typical in a building that uses forced air heating and cooling as well as those that result from weather conditions. Every home should have a blower door test in order to find the leaks and reduce the money wasted each month on an inefficient thermal envelope.
What is embodied energy and why should you care? Embodied energy is the total amount of energy required to produce a product. This concept is certainly hard to grasp and even harder to find real data on various products. As our buildings are becoming more efficient the importance of embodied energy is increasing when making decisions about buildings. It used to be that the energy used to operate a building outweighed any material’s embodied energy, but that is starting to shift, especially with the rise of zero energy buildings.
Embodied Energy is useful in considering which “sustainable” product is the right solution for your project. Embodied energy is a method that aims to find the total energy necessary for the entire life-cycle of a given product. This includes the raw material extraction, transportation, manufacture, assembly, installation, disassembly, and demolition of that product. The lower the embodied energy the less harm done to the environment.
Calculating embodied energy varies depending on who you are getting data from and what bias they may hold. So here are some general rules that might help you as the industry is still trying to figure this out. Recycled building materials often have less embodied energy than a product created with virgin raw materials. Materials like wood are lower in embodied energy than materials that require a complicated manufacturing process. Materials manufactured close to your home have a lower embodied energy than materials extracted overseas or finished overseas.
Registration is now open for the Mid-Atlantic Sustainability Conference. A special offer to the first 30 people to register will get a free copy of the National Green Building Standard ICC 700-2012. This conference features industry experts in the subjects of sustainable sites, alternative energy, legal green, building science, energy code, design solutions, energy modeling, HVAC design, indoor air quality, and zero energy homes. Speakers include Allison Bailes, Sam Rashkin, Ross Spiegel, and Peter Yost just to name a few.
This is the event of the year for building science issues in the mixed humid climate. Hope you will be there.
Talking to a friend this weekend, she has had animals getting into her crawl space. To fix this you have to first get the animals out. Then to keep them out, you should encapsulate the crawl space closing off all the vents, holes, gaps, and cracks. This will keep it critter free, improve indoor air-quality and comfort, and reduce energy usage. An encapsulated crawl space is a sealed and conditioned space like the rest of your home. This approach lines the floor and walls with a sealed 12 mil poly and air tight insulation along the top of the foundation wall to the underside of the floor sheathing above. The walls should have a rigid foam material behind the poly to keep a constant temperature. You could also foam the floor or pour a “mud” slab in the crawl space, but this is often considered a luxury step. The final piece of the puzzle is to take the space to positive pressure to further push the gas and moisture out of the space.
I was visiting a charming little farmer’s market in Durham this weekend and stumbled on a green product called the ELF. This bicycle is an excellent example of innovation, green design, and style. This battery assisted, solar charged bike will go 1.5 hours on a charge depending on total weight on a charge and allows you to apply pedal power to extend your ride. It has a shell to protect you in weather, small storage area, and will go 30 mph while pedaling. It takes approximately 2.5 hours to recharge the battery via outlet and 7 hours via sunlight.
I hear all the time that green costs more. However, with good design, these homes being built-in Lexington will show that green design can be done for any budget. A high-performance home is achieved through an understanding of building systems/building science not increased budgets. Using innovative products available in the market today, allows you to reduce monthly energy bills generated from heating and cooling your home. This is the added value of design.
The most important cost-effective construction solution used to lower energy bills is a reduction of air-leakage. The test used to determine air tightness in a home is required in the 2009 International Residential Code, it is called a blower door test. However, there is a second compliance method, the visual inspection, that most builders in Virginia use to show compliance.
Building code specifies that “the building thermal envelope shall be durably sealed to limit infiltration.” Unfortunately the visual inspection provision weakens this requirement to a point that it makes no impact on most homes being constructed. The blower door is the only effective way to determine total air leakage and verify the home is as air tight as required by the building code (the worst possible construction allowed by law).
