General Process

As an experienced architect with much extra training in low energy buildings, my challenge was to fit my concept from my NESEA NetZero design course onto this site and accommodate all my partner Kaylee's needs. I took Mark Rosenbaum's first NetZero design course and developed a plan for northern NH. Later we bought a lot in Western Massachusetts. The house is similar but here it faces south while the lot slopes to the east. We have a walk-out basement, very useful for accommodating all our gardening needs. The basement includes a very important underground, thermally separate root cellar under our unheated Mud Room. The Mud Room is adjacent to the unheated garage which has a steep trussed roof with attic storage.
We have used local knotty pine trim throughout the house, the floors are bamboo and linoleum in the kitchen and baths. All the lighting fixtures the are not recessed are reused from the Restore or Eco-Building supply of Springfield.

Design for Adaptability:

The house was designed for aging in place and also to keep costs manageable. We have a flexible space on the first floor that can be converted to a bedroom in the future and now serves as a guest room. There is an adjacent bathroom with an accessible shower. All the first floor doors are wheel chair accessible.
The front door and adjacent deck can easily be ramped if needed.

Software Tools

Software Tools:
General modeling information:

The house was modeled with Marc Rosenbaum's modeling spreadsheet for predicting the PV system requirements to meet Net Zero. In order to predict the PV needed to reach net zero the program calculates the solar heat gain, the peak heat load and power required to heat the hot water.

Lessons Learned

Outcome of project goals:

All design is a question of making the best compromises to reach the goals. We did a number of things which are compromises in energy efficiency to make a very pleasing and livable house. We have too many decks and doors and windows. The upper deck off the second floor was designed as a place to dry laundry and it works very well, we have no electric drier. The extra kitchen door is very handy for garden and compost access. The lower porch is great for shaded eating in the summer and wood storage in winter.
Our heat pump system has performed well over the first hard winter. It certainly seems to run continuously and only makes warm water in the sub-zero temps. That's when the wood stove helps out.
All out project goals have been met. With one exception. We installed PV panels on the dormer roof (27 degrees) and on the garage roof (45 degrees). I found that the low slope panels, while a good slope for the summer sun, were snow covered for at least two winter months. Not something we can change now. The houses that I've designed subsequently have uninterrupted 10/12 pitch roofs on the south side.


Marc's model predicted that we would be Net Zero with a 6.7 kW system. Our predicted peak load was under 8,000 BTU/hr. We under estimated our electric loads despite picking the most efficient appliances available. During our first year we used over 12,000 kWh, now we will install a monitoring system to try and understand that. We did irrigate a lot in the summer to grow food.
The heat pump has worked well, though it may consume more power than predicted. We may install more radiators to extract more heat from the same power input.The smallest heat pump system that Daikin made was 18000 BTUs with a cop of 4.6 which seems unreasonable. At -5 degrees F it is probably only half of that. We installed piping for extra radiators if we feel they are needed. We only have one radiator on each floor and they do the job. Our roof could fit 30 panels without shading so that's what was installed.
We need to encourage more manufacturers to bring their air to water heat pump systems to the US as soon as possible!