From Emily Varmecky
This is part 5 of 6 articles that aims to demystify the popular jargon used within the green building industry. A simple Google search will show that there are many strong and varying opinions held by green professionals. Like I’ve discussed in the previous four articles, there are a variety of different sustainable and efficient energy systems that can be used within a building. There are also a variety of different green design methods, construction methods, and material choices. There is a plethora of different reports and thoughts on which strategy or method is most effective, affordable, energy-efficient, easy to build, sustainable, etc. It generally seems, however, that the specific green methods implemented into a building depend on geographic location, available resources, budget, and personal preference. Next in these articles, I will discuss a few different green building strategies as well as green certifications. It should be noted that (along the lines of green washing) just because a green professional is certified to implement a certain strategy, it doesn’t necessarily mean that they are more qualified than a green professional who isn’t certified. For example, even if a building is not LEED Certified, it still may have been designed and built to provide environmental benefits and may have similar features as a LEED building. After researching “Not So Big House,”
I discovered that designers and builders can easily become a “Not So Big House” registered professional after paying an annual fee. Of course, there are many building professionals that practice the design and construction of quality, smaller homes, but are not registered with “Not So Big House.” With training, it is also possible to be a certified Passive House or Green Building professional (among many other green building related certifications). Since 49% of home energy usage in Montana is for the heating of home spaces, reducing the total amount of heat required within a home is a common energy-efficiency approach. One of the best ways to use less heat is to prevent heat created in the building from leaving the building. This is done by constructing high performance walls and roofs that are well-sealed and insulated. There are many different design and construction methods as well as material choices for creating “thermal barriers and fewer air leaks,” but this is usually done by creating an envelope that has a high R-value (or insulation value). This structure can then be fitted with conventional fossil fuel-run heating systems or with sustainable, energy-efficient systems. Either way, the building is still requiring less heat than if it had less insulation. A high performance building envelope not only prevents heat loss in the colder months, it also prevents heat gain in the hotter moths. This helps promote energy-efficiency within the building during all seasons. It is very important to incorporate a ventilation system into a building that has low air leakage to prevent moisture build-up. Just as heat cannot escape this type of building, water vapor (present in all buildings) also cannot escape. Energy-efficient ventilators that limit heat loss and gain are available. A blower door test is one method that energy professionals use to help determine a home’s airtightness. The results of a blower door test are measured as ACH units (air exchanges per hour). As a reference, “older homes, like living in a ‘barn’” have a 10-20 ACH.“Average new homes with some air sealing, but no verification and little attention to detail” have a 7-10 ACH. ACH of 3 or lower is achievable for new homes and is recommended by most green professionals. A Passive House is a super-insulated and extremely tightly sealed home that achieves its energy-efficiency by keeping heat within the home, rather than letting it escape and producing new heat (and vice-versa in the hotter months). Passive House requires a blower door result of 0.6 ACH, a difficult standard to achieve. There are many different Passive House strategies–some rely more on active technologies for heat production, heat recovery, and air circulation and others incorporate passive solar heating and passive cooling design strategies. Emily Varmecky is co-owner of Greenovision Home Design in Bozeman. Please visit greenovision.com/ for further information. •
