Do I need a new electrical service for the ADU on my property?

That depends on the size of your service to your home and if there is enough space in your electrical panel to supply the ADU with the electricity necessary to power its loads. Please engage with your electrician to get a plan together for how to proceed with this portion of the work.

Do I need to have the ADU separately metered? 

If your ADU requires a new electrical service to serve its electrical needs, you will have a separate electrical meter for that service. Again, your electrician 

What about solar?

Siting the ADU is a key to being sure that solar panels will work efficiently to provide you with the electricity to power your unit . Where on your lot with the ADU be located? If it is a stand alone ADU, you will have the opportunity to potentially site the unit in an optimal location for solar gain. Consider the spaces on your property where you can site an ADU and have a look at the tree canopy and other potential shading issues. Your roof needs to be facing South and unshaded from 9am – 3pm on average throughout the year to be a good site.

Once you have your site location identified and your ADU plans together, contact at least three local solar companies to get quotes for your system. You will need to provide them with plans and information about the electricity load of the ADU so the companies can provide you with a suitably sized system. 

Does my ADU need to meet the current Energy Code?

Yes! A HERS rating (Home Energy Rating System) is required to meet the Massachusetts Building Code requirements for new construction. The HERS rating looks at the overall ability for the building to use less energy to occupy. It looks at the building’s airtightness, energy efficiency of wall, floor and ceiling assemblies, windows, appliances, lighting, ductwork, heating & cooling and domestic hot water production. 

Heating & Cooling

When it comes to heating and cooling, appropriately sized heat pumps are the most efficient unit for the task. It is recommended that a Manual J calculation be done to accurately determine the heating load for the space. Heat pumps that are under and over-sized will not perform well and will short cycle due to inaccurate sizing, which leads them to wear out before their life expectancy.

Installing a solar electric system to support the goal of being net zero and no energy costs is paramount to building truly sustainable and affordable housing.