Even with all of the energy efficiency features in the GreenBuild duplex, the feature that makes these homes really zero energy is the solar panels. Each home has a 6kW Solar Array that will produce roughly as much energy as the homes are estimated to use. The panels were installed on each home over the past week; EEHR plans to document the energy usage of the homes after they are constructed and occupied so that we can better understand how much energy is used in each home; how much energy is produced by the solar panels; and how accurate the energy models were when designing the homes.
The GreenBuild Homes have been insulated…again! We already saw insulation installed under the floor slabs and on the wall sheathing, but now the homes have insulation in the wall cavities. On Thursday, damp cellulose insulation was sprayed into the wall cavities to add even more thermal comfort to the homes; this, along with the 1.5″ of polyisocyanurate insulation attached to the ZIP sheathing brings the total wall insulation to R-29–that’s nearly 50% more than a code-built home! While the homes are under construction, we’ve been using them to teach students about high-performance home design and construction. Over the past several weeks, we have taken many students from this year’s Penn State Race to Zero team to walk through the homes and see the physical design and construction so that they can better understand all of the complex systems that go into high-performance homes.
Over the past week, Envinity has been sealing the home with expanding spray foam in preparation for the first blower door test. The home envelopes are designed to be very tight and let in as little air as possible–so little that fresh outdoor air will be mechanically supplied to and exhausted from the home. All penetrations from the outside to the inside are inspected and sealed so that the homes can run as efficiently as possible.
Envinity has finished installing the ductwork throughout the homes! All of the ductwork in each home is for the Energy Recovery Ventilator (ERV); since the homes are designed to be so tight, mechanical ventilation is required to bring in fresh outdoor air into the home. The ERV does this in a way that transfers the temperature of the stale, outgoing air to the fresh incoming air. This means that the homeowners get fresh air without having to use additional energy to heat or cool that air. Whatever additional heating or cooling that is required in the homes is done by a series of Air-Source Heat Pump Mini-Splits. There will be four ductless Mini-Split supplies throughout the home (one on the first floor and one in each bedroom) to efficiently heat and cool the home throughout the year.
During the past two weeks, Envinity has been completing much of the exterior of the homes. The carports and outdoor storage spaces have been framed. Doors and Windows have also been installed, and roofing, as well as the mounts for the PV panels, have been installed.