In the chart at right, the most recent monthly gas billing data for each “building” is shown along with a plot of the computer model predictions. (The DER at Castle Square is comprised of four separate 7-story towers, referred to as buildings on the graph. Each has 48 dwelling units and its own boiler and domestic solar-hot-water system.) Note that in general, all of the “buildings” are performing better than the model. The model did a fair job of estimating annual energy use while it certainly overestimated winter heating energy and slightly underestimated domestic hot-water consumption.
DERs seem necessary on a mass scale to address climate change. They can help to dramatically curb energy consumption and carbon emissions. At the most local level, they also improve the comfort and, likely, the health of their inhabitants. However, DERs are costly, time-consuming and challenging to implement. Nevertheless, the performance of Castle Square Apartments is robust and far above the typical performance of a multifamily energy retrofit.
GRAPHS: Bruce Hampton, AIA, LEED AP
Majority Owner: Castle Square Tenants Organization, Boston
Minority Owner: WinnCompanies, Boston
Architect: Elton + Hampton Architects, Roxbury, Mass.
Technical Assistance: Building Science Corp., Somerville, Mass.
Engineer: Petersen Engineering Inc., Portsmouth, N.H.
DER Oversight: Biome Studio, Boston
Owner’s Rep: Pinck & Co. Inc., Boston
Development Consultant: Rees-Larkin Development LLC, Boston, and Viva Consulting, Newton, Mass.
General Contractor: CWC Builders Inc., Newton
LEED Energy Modeling: The Hickory Consortium, Randolph Center, Vt., (802) 728-6777
R-40 façade cladding: Mini- Wave and Micro-Rib panels from Kingspan, kingspan.us
R-40 white, reflective roofing: 60-mil TPO from Firestone Building Products, www.firestonebpco.com
Air and vapor barrier: Perm-A-Barrier Wall Membrane from Grace Construction Products, www.na.graceconstruction.com
Spray-applied air barrier: Perm-A-Barrier VP from Grace Construction Products
Mineral-fiber insulation: CavityRock MD from Roxul, www.roxul.com
Fiberglass casement windows and French doors: Armaclad, www.armacladwindows.com
Wall-hung condensing boilers: Viessmann
Solar water-heating system: Zapotec Energy and SOLID
Domestic hot-water tanks: Superstor
Energy Star air conditioners: Friedrich
Energy Star refrigerators: Whirlpool
Exhaust ventilation system retrofit: Aeroseal
Constant-air regulator dampers and fresh-air trickle vents: American Aldes Ventilation Corp.
CFLs: Prisma, Lithonia, Omnilite, Progress and Brownlee Lighting
LEDs: Omnilite, Nikko, New Star Lighting and Emco Lighting
Castle Square Apartments’ DER One Year Later
1. Dramatic energy savings
2. Improved health, comfort and affordability
3. Aesthetic improvement
1. Occupant collaboration and support
2. Superinsulation of the exterior wall
3. Ventilation approach was a good solution to a common intractable problem in midrise multifamily (See the May-June 2013 issue, page 62, or read it online for more information.)
4. Apartment air sealing reduced interunit odor transfer and saved energy
WHAT COULD HAVE BEEN BETTER
2. Modeling earlier to inform design
3. Consistent occupant training to use thermostats and windows properly
4. Whole-building blower door test