GBA Logo horizontal Facebook LinkedIn Email Pinterest Twitter X Instagram YouTube Icon Navigation Search Icon Main Search Icon Video Play Icon Plus Icon Minus Icon Picture icon Hamburger Icon Close Icon Sorted

Community and Q&A

Over my head

bradslees | Posted in Mechanicals on

I’m new to this forum, so I hope this is an appropriate question. I’m at the planning stage for a gut rehab of a ~2500 sq ft home in Boston, MA (which I think is zone 5). We’re going to be completely rebuilding the envelope and replacing all the systems. We will have 14kW of solar on the roof.

I’ve been doing my best to research heat pumps, mini splits, ERVs, HRVs, Minotair, etc etc (including reading a lot on this site) to try and figure out what to do for this project, but I’m way over my head. I think I need some help just to know which are the practical options I should be deciding between. If anyone could give me some guidance, it would be enormously helpful. Here are our details:

– basement is a concrete slab (which we will be re-pouring as part of the project) with a playroom and bedroom as conditioned space
– first floor is an enclosed office, semi enclosed living room, and an open kitchen/dining/living area
– second floor is 4 bedrooms
– unfinished attic can be used for systems
– 14kW solar array
– will be re-sheathing and insulating the house as well as replacing the windows. will be tight envelope
– definitely need ventilation. Have a son with dust allergies

I’d love some advice on where I should be aiming my decision-making energy.


GBA Prime

Join the leading community of building science experts

Become a GBA Prime member and get instant access to the latest developments in green building, research, and reports from the field.


  1. GBA Editor
    Martin Holladay | | #1

    It sounds like you have a big project with a big budget. The decisions you are about to make shouldn't be made by a homeowner working in isolation.

    Call Paul Eldrenkamp at Byggmeister in Newton, Mass. Paul is an experienced remodeler with a thorough understanding of energy issues.

    1. Deleted | | #3


  2. calum_wilde | | #2

    Before you can spec anything else you need to define your wall assemblies and roof assembly so you can predict your insulation and airtightness levels. Will there be insulation under the new slab? The ventilation and HVAC should be based on manual J calculations that will be based on the insulation and air tightness levels.

    If I'm not mistaken you'll need the humidity removal properties of an HRV, not the ERV. Minotair appears to be a particular brand name or HRV.

    I wouldn't be surprised if things go well that 14kWh of solar will be enough for the house and two EVs.

    If you're willing to do the manual J yourself (search here there's been great articles on the subject) you could possibly figure stuff out from there. But that's a big ask for an untrained person. I'd seriously consider Martin's advice if it can fit in your budget.

Log in or create an account to post an answer.


Recent Questions and Replies

  • |
  • |
  • |
  • |