The Castle Square Tenants Organization decided to perform a “Deep Energy Retrofit” (DER) on its complex. To qualify as a DER, the renovation had to result in energy savings greater than 50 percent.
Installing insulation from the interior was deemed impractical. The design team determined that dust created by adding new drywall would pose a health hazard to residents. Time spent moving and protecting furniture before installing interior insulation would create long delays. An Exterior Insulation and Finish Systems (EIFS) was considered, but then rejected because of the costs for ongoing maintenance. Another financial concern was that an EIFS would change the fire rating of the building. Castle Square is a brick building, which is less costly to insure. EIFS is more prone to fire risks than brick and increased insurance fees would negate any gains saved by lower heating and cooling costs.
The on-site fabricated panel option was rejected because of warranty issues that arise with fabricating one-off type products on site. Also a field assembled wall system comprised of compressible insulation between interior and exterior liner sheets can result in heat loss.
The Castle Square Tenants Organization applied a "deep energy retrofit" strategy to a 1960s affordable housing development. The 4 seven-story buildings of the Castle Square complex were wrapped in a super-insulated shell. Kingspan's Mini-Wave
panels were selected and provide an insulative value of R-41, twice what current codes require. The 5-inch Kingspan panels accomplish the deep-energy retrofit's enclosure goals while furnishing the building with a beautiful and durable new facade. The project did not displace a single resident during the extensive construction, and total energy savings will amount to more than 72% according to the CSTO. An exterior EnvelopeFirst™ approach maximized the thermal performance and airtightness of the building envelope while realizing minimal disruption for the occupants living in these units during construction. The predictive energy models indicated an approximate envelope improvement of about 30% or more in energy cost savings. The Castle Square Apartments project has earned a Mayor's Green Award, which celebrates works that make Boston a greener, more sustainable, and livable city and is currently tracking for LEED Platinum status.