Carbon Free Boston – Buildings

Boston University’s Institute for Sustainable Energy plans to release its Carbon Free Boston (CFB) report later this year, outlining a menu of policy options that the City of Boston might adopt to reach its 2050 goal of carbon neutralityWritten at the behest of the Boston Green Ribbon Commission, the report will form the basis of discussion of measures to incorporate into the next update of Boston’s Climate Action Plan.

Last June, CFB researchers released a preliminary report listing a wide range of options under consideration in the areas of energy, buildings, transportation, and waste. To better understand and respond to the release of the Carbon Free Boston plan, BCAN has generated a series of introductions to the key elements of the plan. We have summarized the sections about energy and transportation in previous blog posts (energy on October 28 and transportation on December 8). Here we summarize our recent discussion on the buildings sector.

Carbon Free Boston (CFB) has determined that buildings — commercial and residential combined —  are Boston’s biggest source of greenhouse gas emissions (GHG).  The age of our buildings, the lack of good insulation, and their often inefficient heating systems mean that we need to focus on existing buildings, not just try to build new super-efficient ones. And the most effective way to cut emissions from existing buildings is to do deep energy retrofits, according to CFB’s early research findings. Deep retrofits could include different steps such as:

  • Sealing the building “skin” completely so it doesn’t let heat or cold radiate in and out.
  • Installing super insulation.
  • Making buildings more resilient in the face of extreme weather.

Carbon Free Boston’s preliminary findings say deep retrofits would cut building energy use and emissions in half. These are a good beginning to get us to Net Zero Carbon or carbon-free buildings by 2050, Boston’s goal.

How do we get building owners to do deep retrofits, which are very expensive? CFB is looking at these approaches:

   – Requiring deep retrofits when a building changes hands or is sold.

   – Requiring smaller increases in building efficiency every five years.

A good way to reach these goals is to use Passive House principles in our retrofits and all new construction as well. Passive House techniques can be applied to any building type including skyscrapers, not just single-family homes. A passive building: 

  • Uses continuous insulation throughout its entire envelope without any thermal bridging. That means no piece of the building extends all the way from the inside to the outside, where it could conduct heat or cold.
  • Employs double or triple-paned windows and manages solar gain so the sun’s energy heats the building in the winter and not in the summer.
  • Makes the building envelope completely airtight, preventing infiltration of outside air and loss of conditioned air.
  • Uses some form of balanced heat- and moisture-recovery ventilation so this fully-sealed building doesn’t get moldy.

Ideally, Passive House construction is so efficient that no active heating system is required to maintain a comfortable temperature.  Even in less than ideal conditions, this type of building allows for the replacement of large fossil fuel heating systems with small electric ones so they can run on renewable power.

Passive House type buildings are also more resilient in extreme weather (if the power goes out they can maintain comfortable temperatures for days instead of hours) and more valuable because they’re better to work and live in. But that could mean landlords charge higher rents for them, which creates equity issues.

CFB’s early research also finds that we must start electrifying our heating and cooling systems. If we moved to all-electric systems, we would be cutting energy use and emissions, while pushing the energy industry to build 100% renewable sources. Water heating and cooking are two other common uses of gas that will have to be replaced with electric options. Especially in kitchens with inexpensive or poorly ventilated gas stoves, “fracked” methane leaks into the air we breathe every day, polluting us with toxic gases.

Finally, some other strategies that CFB is looking at are:

  • Saying “no new gas burners can be sold after x date.”
  • Requiring solar panels on all new buildings’ roofs.
  • Using cool roofs and cool pavements (painting them white to reflect the sun back off rather than absorb the heat).
  • Cutting the electricity our buildings use at peak demand times.

We will continue to look at and question these ideas as we move forward in our work.  Join us!

passive house principles
Passive House principles include an uninterrupted thermal barrier around the living space, roof overhangs to control the seasonal change in the sun’s position, and heat recovery ventilation.  This illustration also includes a ground-source heat exchanger. (Image courtesy of the Passive House Institute US)

 

 

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