Bunker Hill Development Project Could Be Revolutionary in Energy Efficiency

Few things are as hotly debated in the Town at the moment than the replacement of the Bunker Hill development, but one thing that has escaped discussion this time around is the extremely high level of energy efficiency proposed for the new buildings.

Adelaide Grady, senior vice president at Leggat McCall Properties and executive director of the Bunker Hill Redevelopment Project, told the Patriot-Bridge in an interview this month that they are seeking to build to a “Passive House” standard – which is the highest level of efficiency in residential building.

That standard has been accomplished in Boston before, but never on this scale – and it’s something that Grady and Leggat are very proud of, even though the conversation regarding the project hasn’t yet got around to talking about this amenity.

“It’s really an evolution of what was once known as ‘Energy Star’ from the early 2000s,” she said. “There are a lot of different approaches. For residential, it’s about looking at the heating and cooling of the buildings. That’s what the majority of energy usage is for in residential buildings. The principal with Passive House is focusing on using as little energy as possible in terms of heating and cooling in the building envelope. There are smaller and more efficient heating and cooling systems now.”

Grady knows this because it’s something she is passionate about.

She started her career working as an efficiency expert in affordable housing developments in Boston. It was something she came to while in college, and it stems from her concern for climate change and the overuse of energy resources.

“I think everyone is on board at Leggat McCall with this because it is a company of thinkers,” she said. “Those ideas are coming from the top too. They wanted to build the buildings with the highest performance on energy as possible. I don’t know if I would be working on this project if that wasn’t the way we were trying to go. I believe so passionately in this…No one has tried to do this on this scale in Boston. It’s where things are going in moving forward with regard to doing the right thing environmentally.”

She estimated the heating and cooling systems that are proposed to be used in the new project would use between 40 and 50 percent less energy than a modern-built building – which achieves much higher efficiency than many of the older buildings in Charlestown and Boston.

The groundbreaking systems will use electricity, and courtesy of new technology, electric units are now much more advanced than when they first came on the market years ago. Harnessing the ability to re-use energy and never lose any heated or cooled air, the units can make living spaces more comfortable for less money.

“It used to be they couldn’t run the heat pump for any temperatures below 30 or 25 degrees,” she said. “That didn’t make sense for us. The technology now has advanced in the last eight years and the heat pumps operate at temperatures below zero in heat pump mode.”

In the language of energy efficiency – which is something that Grady specializes in and is passionate about – the key is about the efficiency of the units. Whereas a traditional furnace cannot achieve more than 100 percent efficiency (and most new units are around 85 to 95 percent efficient), the units being considered for the Bunker Hill redevelopment can achieve greater than 100 percent efficiency. At the same time, it produces a higher air quality inside because it exchanges outside air for inside air. However, to achieve such high efficiency, the energy from the warm (or cool air in the summer) air is harnessed and reused by the heating/cooling unit. That allows no energy to escape and less energy needed to condition the air. If the air starts at a higher, or lower, temperature, it takes less energy to get it to the right degree.

At the same time, the units provide cleaner, fresher air than traditional heating and cooling products. That will help, Grady said, with indoor air quality, and ventilation of cooking smells and potential pet odors too.

The units are combined with an impenetrable building envelope when it comes to insulation and windows – making sure little to no air escapes except through the heating/cooling unit. She compared that to a Yeti cooler or a good Thermos, noting that drinks stay hot or cold longer because the seal is better.

This all comes via a mind to achieve this kind of efficiency from the earliest of designs. Trying to do it afterward isn’t possible, she said.

“Interestingly about Passive House and the way we’ve approached it is you have to start the design of the project with the goal of being Passive House,” she said. “It has to start early or it cannot happen. It is designed from the beginning to have a very high level of continuous insulation and to be very tightly sealed. Then the heating and cooling systems are designed at a size to make things that much more efficient.”

The proposal for Bunker Hill is an exciting one for Grady, and not just for the discussions about height, open space and the numbers of units – which have dominated most meetings to date. What is particularly exciting for her is the possibility to see energy efficiency move to a new level with the Bunker Hill project – a level that could set the standard for future new construction projects in all of Boston.

“When I was in college, I started looking at climate change and how our built environment contributes to it,” she said. “The opportunity to do something about that was possible. It’s just about creating an energy behind it. As opposed to the auto industry that has to completely re-tool the behaviors about how the world travels, the building world doesn’t have to do that. I think that’s really exciting.”

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