Step 2: Recycling a building through renovating. In addition to eliminating operational carbon emissions, we took practicable steps to reduce embodied carbon emissions, starting from the design process. First, we chose to retrofit an existing building rather than building new. According to RMI, retrofitting an existing building emits an estimated 50 to 75% less carbon than constructing the same building new. We purchased a single‑story cinderblock building that was built in 1951 and worked with our team of architects, engineers and other construction professionals to identify which aspects of the existing building we could reuse. We ended up keeping three of the four original cinder block walls, and most of the original roof structure, including wooden decking and steel trusses. We even repurposed a trailer load of 2×6 and 2×8 wooden boards from the original build for nonstructural framing. Step 3: Use an energy model to create a plan to reach your energy target! Energy modeling allows a team to estimate a building’s energy performance before it’s built. As a sophisticated computer simulation of the building, our energy model allowed our team to compare and contrast the energy, cost and emissions impacts of different design and construction decisions, such as building insulation levels, window performance and HVAC design. The energy model predicts how the building will operate based on simulated weather conditions for the climate zone and actual utility rates. An energy model is essential to achieving a zero energy building because it also predicts the annual energy consumption of the building (which is critical when sizing on-site renewable energy) as well as the energy use intensity (EUI) of the building. An EUI score is a measure of the energy use per square foot per year, and it’s the industry standard metric for measuring commercial building energy performance. According to ENERGY STAR, the average office EUI for office buildings in the U.S. is 52.9. We chose an EUI goal of 28 based on the 2021 IECC Appendix CC — Zero Energy Commercial Building Provisions. Through several energy modeling iterations, we exceeded our EUI goal by fine-tuning insulation levels, HVAC system design, windows and other building components. The Climate Innovation Center’s estimated EUI is 27.8! Three resources to help you find a qualified energy modeler include ASHRAE, the Association of Energy Engineers and Rocky Mountain Power’s Wattsmart program. The energy modeler for our project worked for the mechanical engineering firm involved in the project. At this early design stage, high performance commercial buildings are eligible for the Designed to Earn the ENERGY STAR certification. Once we knew the final EUI estimate from our energy model and final design elements, we created an ENERGY STAR profile for our building in the Portfolio Manager program and then followed the steps to create a Statement of Energy Design Intent. Of note, our estimated ENERGY STAR Score is 86, which means that our building is among the top 14% most energy‑efficient commercial buildings in the U.S. Not too shabby for a deep building retrofit! Step 4: Building envelope and commissioning. Many professionals understand the value of a well-insulated and airtight building envelope — but it’s a lot trickier than it sounds. It is critical to monitor and watch each step to ensure that the building envelope is done right. There are countless ways this can go wrong, and we experienced this reality first-hand in building the Climate Innovation Center. Central to overcoming this challenge was hiring a building envelope commissioning agent to monitor the design and construction of the building envelope and provide tests to confirm that our building met the targets set. Our agent caught numerous, seemingly small problems that when added together could have jeopardized our zero energy goals. Once identified, the agent provided remedies to the contractors. Based on the findings from the energy modeling process, we knew what our wall and ceiling insulation performance needed to be. We maximized insulation levels throughout the building by using 3 inches of low-GWP spray foam insulation and 4 inches of rigid exterior foam insulation (for a total wall insulation performance of R-28) and 8 inches of rigid foam insulation on the roof (for an insulation performance of R-36), as well as under‑slab insulation of R-15 and foundation edge insulation of R-10. Not all spray foams are created equally. Most spray foams use HFCs which are very damaging to our planet’s climate since they can be hundreds or even thousands of times more potent as a greenhouse gas than carbon dioxide. We worked with industry partners to source a low-global warming potential spray foam product for our interior insulation strategy. The HFO-based spray foam that we used has a global warming potential of only 1. 21
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