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Renewably Powerable I Building Electrification
<br />Why Are We Electrifying?
<br />A powerful tool towards decarbonization is "electrification", which has become a big
<br />movement not just in the construction industry, but also in most industries of our
<br />society. There are a few driving principles behind this movement:
<br />© Electricity is currently produced using a range of sources:
<br />Carbon emitting fossil fuels - natural gas, coal, oil
<br />• Zero -carbon sources - hydro -power, nuclear, wind, solar, etc.
<br />®Natural gas inherently emits carbon when burned, meaning gas -based
<br />heating sources will always emit carbon
<br />The power grid is shifting away from fossil fuels and towards zero -carbon
<br />sources, due to a variety of factors including economic, regulatory, and
<br />societal
<br />®Electrifying our heating systems means their carbon emissions will drop
<br />as the grid continues to add more renewables, eventually dropping to
<br />zero
<br />The first step for electrifying space and water heating system was to evaluate various
<br />system options. Options were evaluated at each building site, where considerations
<br />like energy and carbon savings, incremental cost impact, complexity of design, and
<br />additional other factors were all considered when making a recommendation. Please
<br />see the individual building audit reports for additional detail.
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<br />Full Electrification vs Hybrid Electrification: Space & Water Heating Systems
<br />Heating is the single largest source of carbon emissions by Louisville, through burning of natural gas in boilers and furnaces. Heat pumps offer
<br />an incredible opportunity to both electrify and save energy, since they run on electricity and are also -2-3x more efficient than natural gas based
<br />heating.
<br />However, while heat pump -based heating is an excellent tool for building electrification, today's technology still requires supplemental heating for
<br />the coldest days. In general, it can be expensive to electrify the "last 10%" peak, because the system is sized for the coldest day of the year, which
<br />rarely occurs.
<br />Hybrid heat pump/natural gas peaking systems are a useful tool for sensible and cost-effective decarbonization, as they strike a balance between
<br />carbon reduction, construction costs, and utility demand costs. For fully electrified heating systems, that supplemental heating would be provided
<br />by electric resistance heating, which is capable of low temperature operation. However, in most facilities this approach results in two negative
<br />consequences: a costly electrical service upgrade is required, and operating expenses increase due to high peak electrical draw and resulting
<br />Xcel demand charges. In many cases, using gas as the peaking fuel source on the coldest day will mitigate need for an electrical upgrade while still
<br />achieving significant carbon reductions. The decarbonization "sweet spot" is a heat pump system that meets most of the annual heating demand,
<br />supplemented by a gas system to meet the rare coldest days. This results in substantial carbon reductions (i.e. 75 %+)while reducing overall costs up
<br />to 50%. Retaining the gas supplemental heating until the next replacement cycle in the late 2030s enables:
<br />1. Potential technology evolution, such as 100 % heat pump heating even on coldest days, renewable fuel cells, and/or strategic and
<br />accessible use of bio-gas for peaking boilers.
<br />2. Developments in demand shifting technology(e.g. batteries), resulting in lower demand charges.
<br />3. Changes in relative cost of natural gas vs. electricity, increasingly favoring electricity.
<br />4. Full utilization of useful life of natural gas equipment.
<br />Full vs Hybrid Electrification
<br />(At Sites w/ Both Options) ZX
<br />Total Construction Costs
<br />(100 % Savings)
<br />I 1
<br />Existing Gas Use Full
<br />1X
<br />Hybrid solutions do not make sense at
<br />Total Construction Costs
<br />some sites due to existing electrical
<br />(75 % Savings)
<br />capacity and expected future loads.
<br />7
<br />In these cases, full electrification is
<br />1
<br />recommended.
<br />Hybrid
<br />The last 25 % of gas usage is -4x more
<br />expensive to electrify than the first 75%.
<br />CITY OF LOUISVILLE I FINAL REPORT V3 I INTERNAL DECARBONIZATION PLAN 114
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