A9 Green / Total Green Energy Solution, LLC

A9 Green is the firm builders call when a house has to prove it is efficient. Bijan Khosraviani's Lexington practice does HERS ratings, blower door and duct leakage testing, AeroBarrier air sealing and Passive House and LEED verification, and a good share of its written accounts are signed by construction companies rather than homeowners — Realnova, Sterling Solutions, Kenwood Builders. What customers keep describing is money recovered. A homeowner writing in June 2023 said A9 was the HERS rater on their Mass Save renovation in 2020 and 2021 and that they got the maximum rebate and the maximum HEAT loan. A February 2023 customer said the team held their hand through the process and they received the maximum possible rebate; another that month, recalling a 2020 build, said the house came out more efficient and they claimed energy credits they would have struggled to find alone. In May 2023 a customer credited Bijan and his team with keeping them current on building technology so their rebates could be maximised. The other half is the inspector. A December 2023 customer said communication was good throughout and the project went smoothly with the Needham building department. Sterling Solutions Corp, writing in December 2022 after seven years of projects together, said the team explains the best routes to a rebate while still meeting the required values — which is the whole difficulty of energy-code work. The one 4-star account, from February 2023, puts it plainly: several projects carried to a conclusion that satisfied both the building department and the client. On the homeowner side, a March 2023 customer followed A9's recommendations and had insulation upgrades done, and in March 2025 a customer had blower door testing and praised the crew's knowledge. The Better Business Bureau puts the business at 17 years, grades it A+ and does not accredit it; the services listed there are home energy audits, insulation, weatherization, infrared diagnostics and air sealing. Its Houzz page and its own site list a stack of affiliations — RESNET, ENERGY STAR, Mass Save Partner, NESEA, the US Green Building Council, and PHIUS+ Passive House rating on the company's own account. Two things to settle first. The Houzz profile lists general contracting, home additions and custom homes beside the energy work, while the company's own site describes a consulting and testing firm serving builders, architects and developers — so ask which of those A9 would actually be doing on your job. And the written accounts run from 2021 to March 2025 and lean heavily toward trade clients, so a homeowner should ask for a recent homeowner reference. The right fit is a new build, a deep retrofit or a Mass Save project where the rating and the rebate are the point, and you want the paperwork and the inspector handled by someone who does it weekly.