A3 Architects is a green architecture firm with expertise in mechanical and insulation systems. We design modern efficient homes that incorporate super insulation strategies, efficient heating and cooling systems as well as renewable energy.


 Blown in cellulose Insulation being installed at a project

Blown in cellulose Insulation being installed at a project

HERS Index

The Home Energy Rating System or HERS Index is a nationally recognized industry standard of measuring a home’s energy use. The score is created by an energy model that inputs u-values for major envelope components as well as mechanical systems. A home with a rating of 100 met the IECC 2004 energy code. Many older homes have ratings in the 130s and even higher. Current energy code requires at least a HERS of 85, or 15% reduction in energy use than a new home built in 2004. A net-energy zero home would have a HERS index of 0

For more information on the HERS rating, please read an article written by Alison Alessi in Home Remodeling about Energy Efficient Renovations.


 Solar Panels (by  E2 Solar ) being installed at the  CDP 's  Thankful Chases Pathway Affordable Housing Project

Solar Panels (by E2 Solar) being installed at the CDP's Thankful Chases Pathway Affordable Housing Project


A3 Architects, Inc has completed 12 units of affordable house achieving the highest level of LEED – platinum. The units all had HERS scoress in the upper 20 range. LEED for Homes is a comprehensive checklist that weighs site, water, energy , indoor air quality and materials for a specific project. Some of the most useful requirements are Energy Star program for the Energy portion (see below) as well as the requirement for trash diversion. As a result of sorting construction trash, this 12 unit development: (linke Thankful Chases Pathway) was able to divert 65% of the construction waste from landfills here on the Cape.

LEED PROJECT: Thankful Chases Pathway

To learn more about LEED


 Energy Star for Homes :   Scargo Lake Cottage

Energy Star for Homes :  Scargo Lake Cottage

Energy Star for Homes

The Energy Star for Homes program is highly recommended program for its guidelines on both the design and build side. During design, in fact, fairly early in the process, we develop in conjunction with the HERs rater, an energy model that predicts the building performance. We use this to model several options typically, and also to size mechanical equipment. Once construction starts, the HERs rater plans an integral part in visual and diagnostic inspections of the home, particularly the envelope. We typically test homes with a blower door that measures air leakage of the shell at several stages of construction to ‘catch’ leaks in the envelope. We also use a duct blaster to test for leaks in ducts outside of the building envelope. We find these tests to be invaluable both in creating super insulated homes and catching costly mistakes that happen all too often in the field.

To learn more about the Energy Star for Homes

All new construction and gut renovations are put in the Energy Star for Homes program. A few examples of Energy Star for Homes projects by A3: 

 Wall Mounted Mini split Heat pump supported by Solar on South facing roof.  Dbl Stud wall with blown in cellulose and smart vapor retarder building wrap. 

Wall Mounted Mini split Heat pump supported by Solar on South facing roof.  Dbl Stud wall with blown in cellulose and smart vapor retarder building wrap. 

Passive House

The Passive House concept originated in Germany but from data collected on many North American passive houses constructed in the 1970s. The metrics behind the Passive House modeling program deliver buildings that consume 90% less energy than typical construction. A Passive House is super-insulated (typically more than double code requirements) virtually air-tight building that utilizes heat gains from equipment, residents and the sun to heat space (typically with some mechanical assistance in our climate).

Window orientation and performance is critical to both provide heat in winter and prevent overheating in the summer. Additionally, mechanical ventilation is provided for balanced fresh air intake. Furthermore, detailing on Passive House is required to be thermal bridge free. Active solar, or renewables can be incorporated to create a net-zero structure.

Utilizing the Passive House Planning Package (PHPP) which models heat loss, heat loads, cooling loads, in great detail based on design inputs, we can accurately predict a building’s performance in a specific climate

To learn more about PHIUS (Passive House Institute US)


Net Zero Energy

On one hand, the definition of net zero energy building is quite simple; a building that produces as much energy as it uses. However, there are of course many variations on this. For example, Passive House has two qualifications: site net energy zero, and source net energy zero. Site net zero is the simple definition- produces as much energy as it uses. Source net zero takes into account the energy used to bring energy to the building and transmission losses along the way particularly with the electrical grid in the United States.

Off grid- Typically, in Massachusetts this doesn’t make sense for several reasons. A large part of the incentives for solar are production based, renewable energy producers are paid for energy put back into the grid. If you aren’t grid tied, you won’t make this money. Furthermore, there aren’t too many places where the grid isn’t. Battery back-up for essentials is definitely a possibility. Batteries store the energy when it’s not sunny.

Net Zero Houses by A3: