By Jen Cole
In order to achieve net -zero, the key aspects of the building to focus on are the envelope, the orientation, site, and the mechanical systems. The envelope must be air tight and incorporate 12 to 14-inch walls so that the temperature inside is stable throughout the day. Even if there was a power outage, a tight envelope would secure the building with one to two degrees of temperature variation without heating or cooling. Proactive testing such as the blower door test is done during construction phases to check the air tightness and ensure that there is no leakage. The orientation of the building is also a very important aspect because the use of solar panels is the predominant energy source. Net-zero buildings must be oriented so as to maximize the slope of the solar panels to the south side and allow for south facing recess windows with overhang. The windows themselves are also important to have with triple-pane glass for best insulation. Mechanical systems for net-zero buildings will most likely be smaller highly efficient mini split systems. These compact systems contribute to the building's efficiency by heating and cooling individual rooms while they are being occupied compared to a larger central system that requires more time and energy to heat/cool larger spaces. In addition to the mechanical systems, orientation, and envelope efficiency features such as low-flow water fixtures, air source heat pumps, taped sheathing, and passive ventilation all contribute to the zero net energy of the high-performing building.
We cannot thank John Dalzell enough for sharing with and inspiring our community to push forward with net-zero and net-positive projects. Boston, a national leader in green building, is promoting the next generation of high performance deep green buildings. The E+ Green Building Program demonstrates the feasibility of regenerative multi-unit residential buildings and brings energy and environmentally positive homes to Boston’s neighborhoods. Stay updated with the USGBC MA for more news on the net-zero movement!