Pay Now or Pay Later – Constructed Space per Person

Lucas Hamilton

I recently read a report in the Department of Energy’s 2009 Building Energy Data Book that referenced the amount of constructed surface area per person around the world.  The United States is second only to Canada in the amount of constructed space per person – the U.S. boasts 3,000 square feet per person. This concept of constructed space per person includes home, work, shopping centers, sports complexes – any constructed buildings where we live, work or play. 

This is far more than most of the world. Comparing the United States to the United Kingdom, for example, the average English citizen uses approximately one-third the space of Americans.  Americans have come to expect this right-of-space. But there is a price to pay if society continues to expect large buildings. If the goal is to move toward net-zero buildings we are going to have to become very creative to overcome our need for space.

One example to consider along these lines is the issue of rain water run-off. For the most part, constructed space represents hard surfaces which prohibit rain water from being absorbed into the ground.  This not only overloads our water treatment and sewer systems, as we discussed in a previous blog about Live Roofs, but it effects the sequestration of carbon dioxide. 

The new Leadership in Energy and Environmental Design (LEED) for Homes program sponsored by US Green Building Council is penalizing homeowners for having more space in their home than they need.  However, if a 4,000 square foot home for two people is still desired, the LEED program will allow it but will require more energy efficiency components in order to certify the home. This seems reasonable to me.

If Americans wish to build large spaces, designers and developers are going to have to work harder to offset the impact on the environment.

Lucas Hamilton is Manager, Building Science Applications at CertainTeed Corporation

Green Generates Green for Philadelphia Builder

Lucas Hamilton

I had the pleasure of listening to Tad Radzinski, of Sustainable Solutions, a sustainability expert in the Philadelphia area, talk about an unusual and creative project that he recently worked on using a vegetative roof. 

From the Building Science perspective, what I like about vegetative roofs is the albedo of plants, which plays a large part in the benefit of live roofs, and the fact that they are literally cool roofs that naturally increase the insulation value on your structure (the r-value of the soil bed). Live roofs also reduce the amount of storm water runoff and city’s like Philadelphia are starting to reward building owners for moving to vegetative roofs.

 A few facts:

 1.) For most of us on municipal water, when you pay for a gallon of water you are also paying for a gallon of sewage treatment.

 2.) In older municipalities, the storm water and sewage lines are co-mingled.

 3.) When there is a rain event it can cause the water/sewer to overflow system capacity and be diverted into the rivers.

 4.) When this occurs, the municipality is fined for the overflow.  However, most cities would rather pay the small fine from the occasional rain event than to upgrade the storm water and sewage system.

Philadelphia recognized this and has started to reward builders who take steps to reduce site run-off by reducing the per gallon rate paid for the water they do use. By demonstrating the volume of run-off eliminated through the implementation of vegetative roofs and the reduction of hard surfaces such as paved parking areas, builders can qualify for water rate reductions. Applying this data to a life cycle assessment, we quickly see one more way that being green can save you green.

Lucas Hamilton is Manager, Building Science Applications at CertainTeed Corporation