When New York City’s tallest skyscrapers began scrambling to eliminate their reliance on natural gas, they realized the following: “A holistic approach, combined with a realistic phasing plan, can make decarbonization technically and economically feasible.” New York State Research and Development Authority (NYSERDA)’s guide on resource-efficient decarbonization breaks down this approach succinctly.
This article presents a high-level overview of their suggestions along with our internal study that delves into the viability of hybrid DHW systems:
According to NYSERDA, most engineers fall into the trap of electrifying everything at once. Such traps usually prevent early action in the following manner:
Looking for simple payback → seeking 1:1 equipment replacement → “It can’t be done” → Trying to electrify all at once → Waiting for better tech → Looking for THE solution → Realizing electricity produces emissions too → Finding overhauls too disruptive → Concluding that decarbonization is not possible.
Instead, a better approach might look like the following:
Long-term capital planning → Partial electrification and right-sized equipment → Phasing in measures over time → Starting with partial electrification → Starting now with enabling steps → Staying tech neutral by avoiding “one solution” → Realizing that the grid is rapidly decarbonizing → Using a decision-tree phased approach → Realizing that decarbonization is viable
To summarize the above, successful decarbonization planning can be broken down into three steps:
Heat pumps technologies have regained prominence due to increased importance of sustainable design. Due to their high efficiencies and ability to move heat from one source to another, they present exciting opportunities for recycling heat for multiple applications. Replacing natural gas water heating with heat pump water heating is also a viable decarbonization avenue.
However, completely switching to heat pumps for the entirety of a property’s water heating needs can be unfeasible for some projects. As discussed earlier, it makes more sense to seek enabling pathways towards decarbonization if complete overhauls might clash with a project’s scope and available resources. We analyzed two hybrid water heating configurations:
A 100-room hotel in the Midwest was used to benchmark the upfront cost, performance, and carbon emissions for the hybrid systems. The baseline for each option was compared with the Intellihot iE1 water heater.
The heat pump primary system actually cost slightly more than the heat pump only option. However, it boasted of the best overall operational efficiency. The higher efficiency is likely due to the cost of electricity being higher than gas. Since recirculation load dominates the overall BTU requirements in commercial buildings, dedicating a gas-fired system to handle this load leads to a reduction in the total cost to operate the system. This lends this system configuration as the most practical approach for buildings looking to cut carbon emissions and operational costs.
The gas primary system sets itself apart as the lowest upfront cost option, allowing buildings without large budgets to begin working towards electrification goals. While this system does see increased operational costs and emissions over the heat pump only system, it is the lowest barrier to entry for building owners and engineers looking to electrify.
Whether a project necessitates cutting operational bills, or lowering upfront costs, it is still possible to consider electrification. Small steps like hybrid systems can offer enabling pathways for long-term decarbonization. The results of the above study will be available in our upcoming white paper shortly.
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