Passive Strategies a Critical Component in the Race to Zero Energy

RTZ1 We kicked off our Race to Zero Energy series on May 12th with a panel of experts who shared their perspectives and recommendations on passive strategies to reduce energy consumption in buildings.

Laura Nettleton, of the sustainable architecture and design firm Thoughtful Balance, kicked off the panel by explaining the meaning of passive house with a metaphor. “You can think of passive house building as a cloth bag and you can think of the building’s HVAC inflow as water filling the cloth bag. As the bag is filled, water slowly seeps out from all sides of the bag. This is how a passive house works. Now for a conventional building, take that cloth bag and cut out many holes. This allows water to flow out much quicker, and requires more water to keep the bag full.” Each one of these holes permits leakage, common around windows and doors. In fact, she continued, 30% of heating and cooling energy is lost where the floor slabs touch the exterior wall.

Passive house focuses on air tightness and insulation, as well as ventilation and energy efficiency. Doing this can greatly reduce the amount of heating or cooling required in a building, and smaller, more efficient mechanical systems can be installed to keep up with the HVAC needs of the building. Energy efficiency measures should not be adopted “a la carte,” as Laura puts it. Instead, she stresses the importance of thinking of the building as a system as a whole.

Laura emphasized a critical point for 2030 District participants: achieving 2030 Challenge goals will require owners to address inefficiencies in the building envelope, particularly for the new construction goal of net zero. If owners don’t create tighter envelops, a significant amount of photovoltaics will be needed to offset the energy lost.

RTZ2Vivian Loftness, professor of architecture at Carnegie Mellon University, gave a comprehensive overview of what she calls “environmental surfing.” Referring to improving the resiliency of buildings by grappling with the environmental factors that affect it – including air, temperature, and light – she offers recommendations for confronting these areas in order to reduce the environmental impact of buildings. She explains that energy consumption can be greatly reduced with creative design that embraces natural renewable resources, which she calls, “the centerpiece of human health and environmental resiliency.” She explained that “deep passive investments” should be made, focusing on air tightness, thorough insulation, natural lighting, natural ventilation, night cooling, and HVAC system upgrades.

Craig Stevenson, VP of James Construction, explained how his firm uses energy models to test technologies before installing them. His team develops several design concepts and plugs these concepts into the energy model to find the most cost efficient and energy efficient solution.

While working on the East Liberty Presbyterian Church project, Craig analyzed historical utility use for the building, and found the 12 data points offered annually on the utility bills were helpful but insufficient to calibrate their model. Additional metering was needed to provide the level of data needed. Ultimately it was revealed that 80% of the energy used by the church occurred during six months of the year. Much of this usage could be reduced by implementing boiler controls and setbacks.

Brandon Nicholson, founding principal of NK Architecture, made a strong business case for sustainability, highlighting the financial savings and productivity gains possible with passive strategies. He addressed the need for a better building design philosophy that focuses more on the basics of construction, including exterior insulation, air barriers, fenestration, and heat recovery ventilation. Passive buildings focusing on these areas can use 80-90% less energy, resulting in tremendous cost savings. More durable materials and construction reduce risk with less chance of rot and mold, and fresher air can attract tenants who care about air quality and health. Better thermal regulation systems are quieter and more reliable, increasing occupant comfort – ultimately retaining tenants longer and reducing turnover cost.

Rob Hosken, principal of Building Performance Architecture, talked about hands-on measures building owners can take to improve the efficiency of building systems. He explained the importance of energy auditing and metering, including creative solutions owners and developers can use to engage tenants in conservation efforts. Overcoming the split incentive – where building owners are responsible for upgrades to capital equipment but tenants pay the utility bills – is challenging but achievable,  particularly through the use of appropriate metering and leasing terms.

He closed by talking about funding opportunities, which can be found through DSIRE, the online Database of State Incentives for Renewables & Efficiency.

The Passive Strategies panel was a great start to the Race to Zero Energy series. Coming from diverse backgrounds, each speaker stressed the importance of working toward passive strategies to improve resiliency and meet sustainability goals while contributing to economic well-being as well as occupant comfort and health.

Three more Race to Zero Energy events are planned – we hope you’ll join us.
June 23: Technologies & Products: Enabling Building Performance
July 21: Renewables: Solar, Wind, & Geothermal in Pittsburgh
August 25: Financing Strategies: Moving Key Projects Forward

This event was made possible in part by funding support through the West Penn Power Sustainable Energy Fund and our Race to Zero Energy series sponsor Forte Building Science. It took place in the beautiful and historic East Liberty Presbyterian Church. Built in 1935, this seven-story church has over 160,000 square feet of floorspace. The building has recently undergone a renovation reducing the church’s energy use intensity from 83 to under 60. Their commitment to environmental stewardship and cultural enrichment made the church a great venue for the event.

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