Deep Energy Retrofit at Affordable Housing Property Cuts Energy Consumption 72%


Property owners considering improving energy efficiency at older apartment buildings may want to consider reaching for a jacket to get the job done. Updating 40- and 50-year-old structures to reduce utility spends is literally going under cover with a deep energy retrofit, a process that envelopes exteriors with an insulated wrap without removing a brick. The result is a new look and better energy efficiency.

WinnDevelopment, a Boston, Mass. developer, recently completed an experimental deep energy retrofit that included putting an insulated exterior wrap over a portion of the 500-unit Castle Square Apartments, a 1960s-style affordable housing property on the city’s South End. The $50 million project, partially funded by government low-income tax credits, low-interest loans, and competitive grants, is expected to reduce the property’s energy consumption by 72 percent.

The project, which headlined a sustainability session at November’s National Multi Housing Council OpTech 2012 conference in Dallas, Tex., was recognized this fall as LEED Platinum by the U.S. Building Green Council. The property is the second LEED platinum project for WinnDevelopment in 2012 combining affordable housing and green building practices.

It’s Like Adding a Sweater and a Windbreaker to a Building

The treatment on 192 units of the building consisted of affixing a Kingspan paneling system–aluminum metal sheets with a special coating that sandwiches together foam insulation–to the existing brick exterior that had been exposed to Boston’s sometimes extreme weather for about 50 years. Rather than removing the existing exterior, the bricks were treated with a vapor barrier before the 6-inch insulated panels were placed on top. An R-40 roof and R-5 windows were installed to complete the retrofit.Image of Castle Square Apartment deep energy retrofit

Wrapping seals off the exterior envelope, but Castle Square also focused on interior air-sealing between units. This compartmentalization separates air flow between units, eliminating costly air leaks that create drafts and otherwise sour the resident experience.

The result – at a cost of about $12 million – is an air-tight membrane with a modern look that improved energy efficiency by reducing natural gas and electricity usage. Considered insulation worthy when it was built, the affordable housing property–billed “Suburbia in the City” in a 1960s advertisement–went from an insulation rating of R3 to R40. The 10-fold increase in insulation allowed new mechanical systems to be downsized because new heating and cooling loads were reduced.

“It’s both a sweater and wind breaker to the building,” said Darien Crimmin, WinnDevelopment’s director of sustainability. “You have to think of both insulating and air filtration with the envelope. You have better quality air and temperature range that (residents) like, less draft, less pests, all because it’s air-tight.”

Gaining a Resident Retention Advantage

WinnDevelopment, which has focused on revitalizing troubled properties, applied retrofit practices more common in Europe to Castle Square, which was leaking about $3,000 per unit per month in energy costs. Few such projects have been completed in the U.S., Crimmin said.

President Larry Curtis, who gave the company’s NMHC presentation, said a deep energy retrofit not only helps retain and attract new residents but gives property owners a green – and monetary – advantage. Doing the “normal stuff” like updating kitchens, baths, and lighting is one thing, but a comprehensive rehab that includes a “sensible energy retrofit” does more for the bottom line.

The company began planning the deep energy retrofit about five years ago and welcomed input from residents through town hall-type meetings. Residents identified a number of issues – frequent drafts from windows, doors, and A/C window units, as well as poor indoor air quality – that the retrofit corrected.

In addition to covering the exterior, the deep energy retrofit included installation of a new roof, windows, high efficiency heating and air-conditioning, solar hot water, lighting and low-flow toilets.

“The residents had a huge part in this,” Crimmin said. “Bringing their concerns to the table, defining what the retrofit could be and combining that with the building science that was driving architects and engineers was really interesting. We had a lot of interaction with the resident. They are really excited about the product.”

The Greenest Affordable Housing Building in Boston

Crimmin said that residents are enjoying more comfortable living conditions, and the only breezes they are getting are those allowed in by opening windows on pleasant days in Beantown.

Because of financial considerations, less than half of the building got the exterior retrofit. As more funding becomes available, WinnDevelopment could do the rest of the building and potentially improve upon that LEED rating.

“We like to say it’s the greenest building in Boston,” Crimmin says. “It’s definitely the greenest affordable housing building in Boston.”

What do you think about deep energy retrofits? Would you consider investing in that process to improve energy efficiency at your older apartment buildings? Share your thoughts in the comments below.


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Contributing Editor, Property Management Insider
President, Ballpark Impressions, LLC

author photo two

Tim Blackwell is a long-time publishing and printing executive in the Dallas/Fort Worth area who writes about the multifamily housing and transportation industries. He has contributed numerous articles to Property Management Insider, and worked as a newspaper reporter in the D/FW area. Blackwell is president of Ballpark Impressions, and publishes the Cowcatcher Magazine. He is a member of the Fort Worth Chapter/Society of Professional Journalists.

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