Housing Initiatives Partnership (HIP) has a proven thirty year commitment to providing affordable housing in Prince George’s County. In recent years they have increasingly focused their efforts on developing housing that is both healthy and energy efficient. This is not by chance; it is critical to their mission. An asthmatic child staying home sick from the effects of poor indoor air quality can mean a lost day of work for a single parent. A high monthly energy bill can break the budget of a family of limited means.
It is for these reasons that HIP created the first Passive House in Prince George’s County, located at 5424 Addison Road, Fairmount Heights, just around the corner from the proposed Fairmount Heights lots. The success of that pilot project inspired HIP to apply for, and win, a grant to move to the next step and create a DOE Net Zero Ready community of eight homes.
Up until now, Net Zero Energy Buildings have been rare and expensive. This is primarily because they are not designed in an integrated way; solar panels are simply added, at considerable cost, to buildings built at or slightly above energy code minimums. This is not a viable approach in bringing net zero to the affordable housing sector.
This project presents a model for the logical way to build healthy and resilient net zero communities based upon a simple equation:
a super efficient building envelope + a minimal solar pv generation and storage system = an affordable net zero home
The envelope part of the equation is accomplished by using an integrated design approach based upon low- tech and economical solutions achievable by any careful builder. The result is homes with heating and cooling demands that are 80-85% lower than code built homes, needing much smaller heating and cooling equipment and much less electricity. We know this approach works because we achieved it in the Passive House on Addison Road, which has a total energy bill of under $60/month. These homes will be built similarly to that project in terms of size and style, with variations in response to site and aesthetics.
What makes this project unique, however, is the second part of the equation: our approach to onsite energy generation and distribution. Instead of installing eight separate solar generation systems that link to the grid, we are hoping to construct a hybrid direct current microgrid. Unlike traditional PV systems, this microgrid system will not depend solely upon the regional grid to store energy when these homes are creating more energy than they are using. Rather, these homes will store that extra energy in a battery system, which will provide power when the regional grid is down. While hybrid dc microgrids are being developed extensively for commercial structures like data centers, there is as yet no residential hybrid dc microgrid project in the country. This project will be a valuable demonstration project leading the way for others.
This microgrid approach has the potential to bring initial investment costs down and drive efficiency of energy generation up; it also makes for a more resilient community. When the grid is down, these homes will still have power. What we are creating is a model for a future community-centric, distributed energy grid. At a time when the State of Maryland is formulating how it will incorporate microgrids into the energy mix, our hope is to make this project a beacon.
You can learn more about the advantages of direct current in hybrid dc microgrids in this blog post.