Not sure which energy code requirements apply to your project? Find out!

Stretch Energy Code Q+A

Q: What is the ‘stretch’ energy code?

A: The ‘stretch code’ is an optional appendix to the Massachusetts building energy code that allows cities and towns to choose a more energy-efficient option. This option increases the efficiency requirements in any municipality that adopts it, for all new residential and many new commercial buildings, as well as for those residential additions & renovations that would normally trigger building code requirements.


Q: How is the stretch code different from the existing ‘base’ energy code?

A: The stretch code appendix offers a streamlined and cost-effective route to achieving approximately 25% better energy efficiency in new residential and commercial buildings than is required by the base energy code. This is largely achieved by moving to a performance-based code, where developers are required to design buildings so as to reduce energy use by a given percentage below base code, rather than being required to install specific efficiency measures.

Developers have flexibility to choose cost effective and appropriately designed solutions. New residential construction must use the performance-based approach, but residential renovations and most commercial buildings may instead opt to follow a ‘prescriptive’ route that specifies a set of minimum energy efficiency requirements for different building materials and systems.


Q: When do I need a blower door test? Is that just in Stretch Code towns?

A: A blower door, or infiltration test, is required by code for any dwelling unit in buildings 5 stories or less. 6 story or more buildings also require infiltration testing, but at a different threshold. HVAC or duct testing is also required, along with ventilation.


Q: What is the anticipated cost of the stretch code?

A: Construction costs are estimated to rise approximately $3,000 for a typical single-family home, and by 1% to 3% of total costs for commercial buildings. However, after energy cost savings on heating and electricity are included these higher performance standards save money. In addition, the state’s electric and gas utilities provide financial incentives that further reduce the upfront costs of high performance buildings.


Q: How is the stretch code implemented and enforced?

A: Implementation and enforcement of the code is similar to existing code, where the developer is responsible for submitting documentation of compliance to the building inspector for review, and the building inspector conducts a plan and site review. The actual testing is performed by a certified or approved third party (Home Energy Raters).


Q: What is the role of a building code official and a HERS Rater for residential projects?

A: Residential buildings meeting the stretch code through a HERS rating and EPA thermal bypass or thermal enclosure checklist require independent certification by a HERS Rater (Home Energy Raters). The rater will produce a report detailing the energy systems in the building and will provide a HERS index score, together with proof of whether the home qualifies for any federal tax credits. Submission of the HERS report, together with a completed Energy Star Thermal checklist, are the steps required to demonstrate compliance with the energy portions of the code, and must be submitted to the local building inspector prior to receiving a certificate of occupancy. In this way the local inspector retains their oversight role but the additional energy requirements do not place a significant additional burden on their time.


Q: How do I meet the residential stretch code for new homes?

A: For new residential homes, including multi-family homes of 3 stories or less, builders essentially follow the 2015 or upcoming 2018 IECC ERI path. Each new dwelling unit must show that each unit meets or is below a maximum HERS index score. For new homes, the maximum HERS score is 55.  A Thermal Enclosure Checklist can be used to confirm the Air sealing table in the current IECC. The new base energy code likely requires duct testing and ventilation. These inspections ensure that the home is well air-sealed, while the HERS rating ensures that the home is designed to be well insulated with efficient heating, cooling and lighting – all measures that save energy and reduce utility bills.


Q: Does the stretch code apply to major renovation projects as well as new construction?

A: For commercial buildings: no, for residential buildings: yes. The stretch code has less stringent energy performance requirements for renovations than for new buildings. In addition, those doing additions and renovations have the option of using a simple ‘prescriptive’ path to code compliance. The prescriptive path specifies a set of minimum energy efficiency requirements for different building materials and systems, instead of requiring energy performance modeling and testing. This flexibility is available due to the greater design constraints involved in working with an existing building. Due to the wide variety in types and conditions of commercial buildings, at this time there are no widely accepted standards for renovating such buildings, so only new commercial buildings are covered by the stretch code requirements.


Q: Does the stretch code apply to minor additions to existing buildings?

A: Additions to existing buildings that are large enough to require code compliance are treated in the same way as new construction for commercial buildings, and in the same way as renovations in residential buildings. In both cases, those doing additions can follow the performance approach to code compliance or a simplified prescriptive path. For residential additions, the prescriptive path is very similar to the base energy code but also requires the use of a checklist to ensure quality installation of insulation and air sealing, use of Energy Star windows, doors and skylights as appropriate, and tighter duct sealing for new heating and cooling systems.


Q: What categories do multi-family residential buildings fall into?

A: Residential multi-family buildings that are above 100,000 square feet and at least four stories tall have to follow the same performance path (20% better than the ASHRAE standard 90.1-2007) as other commercial buildings larger than 100,000 square feet. Residential buildings below 100,000 square feet and at least four stories tall are classified with commercial buildings between 5,000 and 100,000 square feet. Multi-family homes with one to three stories of any size fall under the residential stretch code standards. In the rare case of a multi-family building of three stories or less that is larger than 100,000 square feet, the developer may elect to be treated either.




Home Energy Raters