Hotel Subsegment HW Load Profiles

The market currently lacks an updated database of hot water load profiles for the hotel category. The “Database for Energy Efficiency Resources (“DEER”) Water Heater Calculator”, California building energy code compliance (“CBECC”)-Com compliance models, and the “Ecosizer” sizing tool reference single hot water load profiles, regardless of hotel size, room count, usage type or amenities served.  Inaccurate modeling may inflate projected energy savings or incorrectly validate improper designs. The use of updated and modern hot water load profiles in energy savings calculators, compliance models, design models, and sizing tools will avoid improper sizing, reducing installed costs associated with oversized systems while improving system performance and energy savings relative to improperly sized systems.. When projected savings align with real-world results, the utility incentive programs can rely on estimations, increasing confidence in the modeling tools themselves and heat pump water heater (“HPWH”) technology in general.A recent American Society of Heating, Refrigeration, and Air-Conditioning Engineers (“ASHRAE”) study conducted detailed data collection on hot water loads (5-second interval data) at two (2) additional hotel sites in 2015. Researchers used advanced data analysis techniques to develop formulas designers can apply to the foundational 1960s data when sizing hot water equipment. The 2015 ASHRAE formulas and associated calculation guidance allow expert users to determine total storage and heating capacities for peak design-day 24-hour loads, but do not provide the modern hot water load profiles that would be critical for commercial heat pump water heater (“CHPWH”) designs. The cost-effective design of CHPWHs relies on balancing the high upfront cost of heat pump heating capacity with the space constraints of additional hot water storage. It is very important for designers to understand when hot water draw periods are expected, and the extent of those draw periods, so that sufficient storage can be selected and the available heating capacity can re-charge the storage before the next draw period occurs. As CHPWHs become a focus for load shifting goals and strategies, the importance of accurate hot water load profiles becomes even greater for initial system design, forecasting energy savings, and supporting building electrification efforts that contribute to California’s target of carbon neutrality by 2045.Standard industry design approaches rely on complex calculations, manually calculating heat loss, recovery time, hot water consumption by end-use type, etc. This approach requires expert knowledge of not only domestic hot water (“DHW”) systems, but also HPWH equipment capabilities and storage performance/requirements. The lack of modern hot water load profiles can lead designers to oversize heat pump capacity and hot water storage to avoid the risk of underserving peak loads. Oversized systems increase upfront equipment and installation costs by requiring larger heat pump and storage capacities than necessary, creating an additional first-cost barrier to CHPWH adoption. Additionally, high knowledge requirements and difficult design methodology may dissuade new designers from pursuing CHPWH work or building owners from opting into a CHPWH selection. The availability of more accurate hot water load profiles can improve both manual design methodologies and automated sizing tools such as  Ecosizer, allowing designers to more easily develop accurate and cost-effective CHPWH designs without relying on conservative sizing assumptions. By lowering design complexity and reducing first-cost barriers, updated load profiles can help accelerate the adoption and installation of CHPWH technology.CHPWH designs with appropriately sized hot water storage can reduce or eliminate the use of electric resistance heating to meet peak hot water draws for increased energy savings and reduced utility bills. Accurate hot water draws enable reductions in installed cost and utility bills for improved affordability.