|
 |
|
The Context
The new zero net energy housing is proposed for the Guilford Housing Authority’s Boston Terrace site at 41 Boston Street which has 40 existing units on approximately 2.5 acres. The existing units, constructed in 1982, are small garden style, built in attached unit clusters of 3 and 4 around courtyards. The Housing Authority has expressed an interest in developing 9 additional units at the East end of the Boston Terrace site, which we have determined will have adequate land for the new housing and septic fields. The Housing Authority wanted the new housing to be designed at a scale and with materials that would fit in with the existing development and neighborhood, and to set an example for small, well designed, energy efficient, affordable housing. As with all affordable housing, development cost considerations are important, so the solutions proposed are considered to be the most cost effective both in initial and lifetime cost.
The Proposed New Housing
The proposed building area is level and grassy with a mixture of existing evergreen and deciduous trees along the North and East property lines, giving the units a natural landscape buffer against prevailing winter winds. The nine new housing units are all one bedroom, 600 square feet and attached in clusters of three around a courtyard. Six of the units have a North - South orientation and three are oriented East – West. The units are slab-on-grade with R-24 insulated concrete forms and perimeter sub-slab insulation. The exterior walls are 10" structural insulated panels with thermal value of R-38. The roof construction is trussed and is covered with a standing seam metal roof, having a selected color with high solar reflectivity. The roof trusses and exterior walls are designed to allow for duct space within the conditioned envelope. The unit ceiling is insulated with 15" of blown in cellulose yielding R-57 with the attic space open to allow the building to breathe. The casement windows are triple glazed, low-e, argon filled and have a U value of .20. The exterior doors have a U value of .24 and have storm doors to provide an air lock.
A heat recovery ventilation system will be provided to supply fresh air to the unit while capturing heat from exhausted air in the bathroom and kitchen. The supply side of the ventilation system is connected to the return air plenum of the HVAC system to allow for additional conditioning of fresh air if required. The bathroom exhaust is coupled to the room light switch to allow for the ventilation to run at high speed while the bathroom is occupied to exhaust moist stale air.
The HVAC system is a ducted, mini-split 3,100 – 18,000 btu system which has an SEER of 17.8 and a HSPF of 9.2. The unit operates only as required to meet the demand. The interior unit and ductwork will be located within the conditioned envelope for thermal efficiency.
We are providing 2 flat plate solar thermal collectors on each roof with a drain-back system connected to a 65 gallon hot water storage tank. A 9.7 kw electric on-demand hot water heater will also be provided as a back-up source of hot water if required.
We have planned for the installation of a 2.76 kw photovoltaic array on each roof consisting of twelve 230 watt PV panels which should meet all the remaining electric needs for the units. The appliances and lighting will be ENERGY STAR® rated to conserve electricity. The project will be seeking LEED certification and will incorporate additional green and sustainable materials and methods throughout.
Other team participants include:
Peter Harding - HERS design analysis
Home Energy Technologies, Chester, CT
Paul Israel – Solar PV design
Sunlight Solar, Milford, CT
Chris Wierzbicki – Mechanical System design
Nutmeg Mechanical Services
Additional information about this and other Green Planet projects may be seen at www.greenplanetoptions.com.
|
 |
 |
|
 |
