Green Building, most importantly, reduces dirty Energy Use.

It is the most effective way to reduce a home's environmental impact. Everyone can appreciate paying lower Energy Bills. Energy Efficiency is the main way that green building can be just as affordable as conventional construction. Cost effective energy efficient construction and Green Homes will focus on the Building Envelope above all else.

The Building Envelope is also referred to as the Thermal Boundary and Thermal Envelope. It is basically the air barrier and insulation that defines the transition between indoor and outdoor air. It can be made up of many different components and is detailed differently depending on design. Most Green Designers are aware of the impact of the main parts of an envelope but a lot of new research and strategies are emerging that show the importance of the major transitions; wall to window, wall to roof, foundation to wall etc.

While Heating and Cooling systems represent the biggest Energy Users in most US homes and buildings, their design and energy consumption is based on the efficiency of the Building Envelope. The better the envelope is the smaller and more efficient the heating and cooling system can be. This strategy is true for almost all US climate zones.

Perhaps the most overlooked aspect of Building Envelopes is that they are the most permanent part of the Home or Building. Once they are in place, they are extremely difficult to improve or replace. Heating and Cooling Systems will need constant maintenance and replacement. The Building Envelope has no moving parts and will be in place for a possible 100 years or more.

The Building Envelopes most important characteristics:

1. Airtight
2. Continuous Insulation (Minimize Thermal Bridging)
3. Appropriate R value

Notice that R value is last on the list. R value is a material's resistance to heat flow. R value is often thrown around, bragged about and used as a metric to compare efficiency. While R value is certainly a useful metric, it is not well equipped to handle the measurements associated with something as diverse as the entire building envelope. Software modeling is improving the way it accounts for these dynamics. Building scientists have solid research showing the effects of "whole wall R value" and are currently working on better metrics to replace R value.

Most building scientists will agree that an envelope's airtightness is its most important value. Creating an Airtight Building Envelope is arguably the most cost effective way to increase a homes energy efficiency and decrease its environmental footprint. The best thing about this strategy is that it is easily measured with the Blower Door Test.

The Blower Door test reveals how leaky or drafty a house is constructed. It is a very revealing test and resulting number that is becoming recognized as the most important diagnostic for all new homes and Green Buildings. We will look at it in more detail in a future post.

Check out the author’s other blogs:  san jose jobs and marketing jobs bay area. Springtime Homes are Asheville Home Builders that push for consumer education in the Green building movement.

Our Asheville Custom Homes website has pictures of our work as well as a Green Building Philosophy advocating a cost effective approach to green and new home building.

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