On Thursday July 31st, I had the opportunity to be on the air with Frank Knapp and his show “UNeed2Know”. The subject was Green Building and the “Importance of the Building Envelope”. AS it turned out, this was a subject that could hardly be addressed in 10 minutes. Still, it was an opportunity to reach a number of people who now have some small idea what Green Building can do for them. For all the good things about Green Building, the Building Envelope and its impact on both Energy Conservation and the reduction of Green House Gas Emissions is its heart and soul. If you get this right, the rest of the building falls into place. The reason – you can add most of the other features after the fact, but it is very hard to undo the structure to correct for deficiencies. So how does this fit into the scheme of Green Building? Let’s start with the National Association of Home Builders criteria that define Green Building. It involves 7 basic principles:
a) Energy Efficiency: This almost speaks for itself. In typical cases, the cost for heating and cooling can be reduced by 50% from typically built homes of only a few years ago.
b) Water Efficiency: There are multiple opportunities. These include more water efficient toilets, shower heads, faucets, hot water delivery systems, grey water systems, rain water systems, control of surface water run off, and so on. The reduction in water usage can be substantial depending on options chosen, and is of particular importance in areas with dwindling water resources.
c) Indoor Air Quality: The purpose of this requirement is to minimize potential sources of pollutants in the home, manage potential pollutants, and mitigate potential moisture problems. For people prone to respiratory illness, this can be very significant.
d) Resource Efficiency: In a single phrase, this means no wasted materials and “nothing to the dump”. It also encompasses renewable materials, recycling, and structural durability. All told, good practices here will reduce overall construction cost and durability will minimize subsequent home owner maintenance.
e) Lot Design, Preparation and Development: This involves careful planning and development of the building site for minimal disturbance to soil and vegetation, and upon completion of construction minimal restoration. It also involves the use of local plant materials (or environmentally compatible materials) to minimize the use of natural resources for their sustainability.
f) Operation, Maintenance, and Home Owner Education: This is a manual that explains the proper operation and maintenance procedures so the home owner can operate his home in the same environmentally responsible manner that it was built.
g) Global Impact: These are the features that do not fit neatly into the other six. A good example is the use of low Volatile Organic Compounds (or VOC’s). Use of these paints on the inside of a home greatly reduces the presence of VOC’s. It also has an impact on the global environment – fewer VOC’s coming from a home means fewer VOC’s entering the atmosphere.
If you have the opportunity to select a lot that has the appropriate exposures, and you can place the home so it is minimally intrusive to its local environment. However, this may not always be possible, especially if you are building in a subdivision where lot location may not have been planned with this in mind.
So now you are at the Building Envelope, the skeleton of your home and all the components that determine its interior environment. These will be some of the most important decisions that will impact “forever” on the operation costs of your home. These will involve:
a) The crawl space (or slab or basement) and methods to minimize moisture intrusion and heat loss. The recommendations today are to fully insulate this area and include it as part of the conditioned environment of the home.
b) The framing to provide for the most efficient method of insulation and moisture control. Exterior moisture wraps and careful placement of insulation are extremely important.
c) The roof design and method of preventing unnecessary heat build-up or cold intrusion. The recommended insulation location is immediately below the roof sheathing and includes appropriate air flow channels and radiant barriers.
d) Window size, location, style and glass selection are important to minimize summer solar gain, winter heating losses, and air infiltration.
e) HVAC ductwork and choice of heating and cooling systems are next. It is very important that the duct work be designed with proper size, air flow and balanced delivery to function efficiently. Also, ALL DUCT WORK should be inside the conditioned space of the home and sealed with appropriate mastics.
These “5 Keys” are where the serious money is. Done correctly and heating bills can be reduced by 50% or more. This portion of structure also determines the relative “inside humidity” and comfort. It also provides the opportunity to control and maintain indoor air quality.
As you can see, when home building done in this manner, it is truly a science. All the various features and components interrelate with one another, and the entire building becomes an interrelated system.
