Beyond Skin and Bones - The Beating Heart of Whole Life Carbon in Buildings
Session Recap: Thursday, Sept. 28, 2023
Over the past several years as the operational carbon associated with buildings continue to drop through efficiency in envelopes, improvements in systems, and decarbonization of power grids there has been an acknowledgement of the significant impact that embodied carbon of a building. This focus has largely been centered around building structure and façade, as these represent the largest day one impact on building embodied carbon.
As understanding of the significance of building carbon increases it is becoming critical that we look at buildings from a whole lifecycle carbon standpoint. For this reason, understanding the cyclical nature of building operation, maintenance, and turn from a carbon/greenhouse gas (eCo2) standpoint is critical to truly understand equitable, sustainable, and regenerative building.
In this session, speakers Melissa Kelly, Senior Sustainability Specialist for Gensler, Heather Walters, VP for Thornton Tomasetti, and Ari Greenberg, Senior Associate for BR+A Consulting Engineers explored cost vs CO2e savings as the correct metric to use to analyze envelope, right sizing insulation for a lower 60-year embodied carbon, insulation types, and triple pane windows.
Getting started, there are a few questions to ask for your projects that are critical points to establish the whole life cycle of carbon in the building. These questions include:
- What is the building typology? (school vs. lab vs. residential vs. office space)
- What is the climate? (east vs. west coast)
- How many regional products are available in the area? (source local if possible)
- How efficient is your grid?
With these questions come strategies to standardize and make buildings more efficient.
- Façades protect a building from its environment and with a good design, will have a carbon benefit and lower the long term cost.
- Triple Pane benefit – windows have high embodied carbon, but triple pane windows causes energy efficiency to increase although with a minor additional cost.
- Insulation comparison – determine the embodied carbon ex.) R5 insulation
Electrification in buildings in the best bet at reducing carbon in buildings and was outlined in the following steps:
- Step 1: Heat Recovery – determine the ground source such as geo-thermal, air-source, exhaust source to see what you’re working with and how to optimize.
- Step 2: Heat Pumps – Electrification by load profiles become an important strategy. Load profiles can help you start sizing the heat pump or some type of heat recovery device. More and more electrification can diminish returns because every step costs you more in capacity.
- Step 3: Embodied Carbon – for existing buildings, identify common areas such as pipes or electric systems that often get replaced
Ways to solve for embodied carbon include:
- Reduce infrastructure – reducing the total air in the building affects the cooling and heading because there is less space to cool/heat.
- Heat Pump EC – over the life of the system (if run on clean energy) is much more efficient
- Electric Boilers – very efficient in terms of EC, when loads are high as well as a good way to get more electrification.
- Other options includes: exhaust source heat pump, thermal storage, modular flexibility and more.
Overall, as project lifespans get shorter, embodied carbon becomes more important. The commercial interior fit outs the speakers studied so far have been between 25% and 50% of the upfront EC footprint of the structure. Common challenges they address are that there really is no single solution for reducing embodied carbon on most commercial interior projects, but the above strategies can help make a difference. Luckily, LEED for commercial interiors v4.1: Interiors Life-Cycle Impact Reduction is a strong template for addressing change.
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