(via the Florida Solar Energy Center)

The Stretch Code

February 23, 2010 Posted by Joseph Walsh - No Comments

Building codes, like all legal regulations, are in a continual state of update and revision.  On January 1st, 2010, Massachusetts adopted one such change as part of the Green Communities Act: an optional appendix to the Massachusetts Building Code, known as the “Stretch Energy Code”.  It will enable individual towns and cities in the state to adopt the more efficient standards of the stretch code for new construction, additions, and renovations affecting the building envelope.  It will take effect in communities that have adopted it (Cambridge, Newton and East Longmeadow) beginning on July 1st, 2010.

We thought it might be helpful to give a brief breakdown of the stretch code and the requirements, limitations and possibilities that are entailed in this new change.  It may be a tough pill to swallow for some in the construction industry who are accustomed to doing things a particular way, but there is no doubt it will prompt communities to be more energy efficient, one building at a time.

Stretch Code Adopting Communities for July 2010

Who can adopt the stretch code?

Any city or town in the state may adopt the stretch code after appropriate public hearings and decision by local or municipal government.  So far, Newton, Cambridge and East Longmeadow have adopted, and about 100 cities and towns throughout the state are likely to follow in the near future.

How does it differ from the current energy code?

In the towns and cities that adopt it, the stretch code will require new residential buildings to be 20%-35% more energy efficient than the minimum performance currently required by the building code (20% for commercial buildings).  Testing is required to ensure the buildings are constructed such that they will perform as efficiently as they are designed to be.

How does a project achieve compliance?

New homes will comply with the stretch code by meeting an energy performance standard using the Home Energy Rating System (HERS).  A computer model is created to determine the energy usage of the building and it produces a rating between 0 and 100 to rate the amount of energy consumed.

(via the Florida Solar Energy Center)

Example: A HERS index of 90 means the building uses 90% of the energy
that it would have used if it were built to the standard of the base energy code.

In order to achieve compliance to the stretch code, new homes under 3,000 square feet will have to reach a HERS index of 70 or lower, and larger homes (over 3,000 square feet) must have a HERS index of 65 or lower.

How will it affect the design process?

To meet the new standards, some changes will become necessary in the design process for new buildings.  These changes will include more insulation, airtight windows and air barriers, and more efficient lighting to name a few.  In addition to better-performing materials and components, passive design techniques and a reconsideration of the building’s orientation, massing and spatial configuration can also achieve a more energy efficient design.

How will it affect the construction process?

While many of the changes will affect the products incorporated into the building, these are often simply more efficient versions of the products currently in use.  It is likely that the installation procedures for many of these will remain unchanged.

In addition, there will be inspection and testing of the construction beyond the inspections currently performed by local inspectors.  These will be performed by third-party  companies to ensure the building will perform as well as it is designed.  The tests include a blower door test and air barrier inspection, among others.

(Blower Door Test diagram via Glenco Foam)

What are the drawbacks?

It is true that the required changes will almost certainly result in added first costs for construction, and possibly additional time and attention during the design phase. This may be inevitable, as many studies have been done which project that the initial investment is estimated to be approximately $8,000 for residences and 1%-3% additional cost for commercial buildings.

What are the benefits?

The required initial investment can be recouped in a relatively short time — less than ten years according to some estimates. (See page 2) It is projected that the average home with a HERS rating of 65 would save $1,300 in energy costs per year. (See page 32 for a sample calculation) Consuming less energy is not only good practice; it also saves a lot of money.  Better yet, there are many government programs dedicated to providing money-saving federal tax credits and rebates on energy efficient products, which help save even more money during construction. Furthermore, communities enrolled in the Green Communities Act and implementing the Stretch Code are eligible to compete for up to $10 million in annual state funding for sustainable projects.  This program results in providing a significant incentive for making positive changes at both the scales of the building and the community.

So Now What?

The stretch code is coming, and the more informed individuals and communities are, the more they will be able to understand and adapt to the changes it entails.  While the intent of the Stretch Energy Code is rather simple, the implementation is more  complicated than could be covered here.  More comprehensive resources are available at the following websites.  Happy Reading!

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