Building Green Makes Sense

By William C. Hill

Lately there has been a lot of talk (and a lot of resistance) to building green.  Really, though, in today’s environment, it only makes sense for a builder to build a home at a competitive price that maximizes customer satisfaction and builds the best home possible.

In many ways, the commitment to responsible construction is what building green is really about. Building science helps the builder meet green building goals.

What is Building Science?  Building science is the combination of good building practices and basic science principles to build a better home. A better home uses energy prudently, resists water intrusion, creates a comfortable environment and is built to last.

What does it really mean to build green?  It’s not just about gaining points on a checklist…that’s only one group’s opinion of what’s important (though that all important certification is certainly critical in a tough market).  Building green is about environmental and economic stewardship with a focus on energy conservation, water management and operating costs. The goal is to build a home that incorporates all of these concepts.

So, how does building science work with building green?  It’s easiest to show with an example.

Energy efficiency is the most quantifiable aspect of green building, often garnering the most focus. Last year, the Environmental Protection Agency raised the bar for ENERGY STAR homes (which is a requirement for many green building programs.) It has always been important for ENERGY STAR homes to maintain the expensive heated and cooled air within the building envelope, but after 10 years it became apparent that the way the building was built to keep the cool air in was just as important.  Now, ENERGY STAR homes must also pass a Thermal Bypass inspection based on building science. 

In building science, it is paramount that all the components work in concert. Thus the insulation must be in full contact with the framing. If it is not in full contact, if there are gaps or if the insulation is compacted and not pulled around electrical boxes and water pipes, the hot outside air will pass by the insulation and enter the building. This makes the insulation an air filter and reduces its ability to insulate the building.  Florida’s hot air is usually humid too, and when it’s cooled quickly, condensation forms and then there are all kinds of trouble.  Better to just avoid it altogether.  You could easily say, that you are just asking the insulation contractor to do his job properly.

Another option to the thermal by pass requirements is to use an unvented attic. Building science principles say prevent unwanted water and unconditioned air from coming into a building. In Florida, we build homes with soffits and vents that direct outside air (and water and pollens and air pollution) into the attic to ventilate and move air through the attic. An unvented attic design says that introducing outside air in the attic is counter intuitive. Instead, let’s use a design that prevents hot, humid moisture laden air from entering our building.

With a traditional vented attic, the home leaks air from recessed can lights, uncaulked top plates and ungasketed HVAC registers. In an unvented attic, those leaks don’t matter because they are within the building envelope. 

Still another important tenant of building science is to let the inside of the house dry and manage the indoor air. With an unvented attic, we control the air movement. We insulate the attic with a foam-in-place spray on the underside of the roof deck. Then the HVAC equipment can be placed in the attic.

What are the advantages for the HVAC system? Rather than operating in an attic with a temperature of over 120ºF, it now operates in an attic of about 85ºF. It removes a tremendous load from the equipment and allows it to run more effectively and cheaply. This meets the Green Building goals of reducing cost, impact to the environment and indoor living quality.

William “Bill” C. Hill is sales manager of Daniel Insulation in Clearwater. Bill has more than 20 years in the construction industry with a focus on insulation, water management and environmental management.  He holds a bachelors degree from the University of North Carolina, Chapel Hill and is a member of the Pasco Building Association.

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