Celebrating Summer Solstice in Chicago

Wednesday night, dozens of local designers, builders, and residents gathered to see how passive principles are applied in projects—and how they can give us a jump start on a clean energy future. PHAUS’ Chicago Chapter organized an in-depth guided tour of Tierra Linda, a PHIUS+ project currently under construction in Chicago’s Humboldt Park neighborhood. This affordable 6-unit building, developed by LUCHA, is vying to be the first PHIUS+ multifamily project in Chicago. It also shows how good design is the first step in making the sun our primary source of power.

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So, how far does solar power go? Technically, energy from the sun, our friendly fusion reactor, travels about 93 million miles, or 7 light-minutes, to reach Earth. However, if you want to know how far solar power will go to meeting your home, business, or community’s energy needs and sustainability goals, you need to start with some critical questions and concrete examples.

As an energy efficiency evangelist, I often take umbrage when a news story says that a new power plant will produce “enough energy to power X homes.” Usually, that number’s about 750-1000 homes per megawatt, or 7.5-10kW per home. But how many GOOD homes would that same facility power?

To even approach numeric goals for climate, we need to address both supply and demand, numerator and denominator, at the same time.

This is where passive building comes in. By investing in the “passive” (i.e., nonmoving) parts of a building like walls and windows, we can significantly reduce the need for “active” systems like HVAC—and the energy to run them. The PHIUS+ standard sets cost-optimized energy targets based on local climate, building geometry, and occupancy.

If you start with minimal loads, it’s easier to meet them completely with clean energy. This is not complicated conceptually or practically. There is more opportunity to conserve energy in a building than to make it on the roof. The PHIUS+ limit on source energy makes sure that projects focus on efficiency first.

The table below compares the two scenarios PHIUS staff and the project team evaluated for the Tierra Linda project.

IECC 2015 PHIUS+
Annual Energy Use (kWh) 112,000 43,000
EUI (kBTU/sf/yr)                              39.3 16.8
PV needed for NZE                         86kW 22kW

If the project had been built to Chicago’s already stringent energy code, it would need a very large solar array. The extra 64 kW of solar would have cost $200,000 more. Even if there were room in the budget for that, there wouldn’t be space on the site! The team was able to eliminate equivalent energy use through passive techniques like insulation, air sealing, and energy recovery ventilation that will deliver comfort and savings to the residents—even on cloudy days in the depths of the Chicago winter.

Check back to the Klingenblog for more about how PHIUS+ is helping a clean energy future get made—even in the shade.

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