Dissertations and Theses
Date of Award
2024
Document Type
Thesis
Department
Mechanical Engineering
First Advisor
Jorge González-Cruz
Abstract
Motivated by reducing impacts of climate change due to greenhouse gas emissions, many dense urban cites throughout the United States have set into law ambitions decarbonization policies that will require buildings to replace fossil fuel space and water heating systems with electric powered alternatives. In many cities, especially in the northeast, fossil fuel space and water heating systems are used in a vast majority of buildings and significantly contribute to citywide carbon emissions. In New York City (NYC), it is estimated that over 40 percent of citywide emissions come from space heating and water heating systems that run on fossil fuels . Amongst the most challenging building types for cities to retrofit are multifamily buildings due to space constraints, the coordination required surrounding the tenants of the building, the high replacement cost, and the conditions of the existing infrastructure.
NYC will undoubtedly be one of the most challenging cities to decarbonize, due to its aging building stock and having one of the highest population densities in the United States. Most multifamily buildings have old, inefficient steam or hydronic boilers that remain in place well beyond their expected life due to the challenges associated with retrofitting. Yet in September 2014, NYC established a goal of reducing 80 percent of carbon emissions by 2050 (from 2005 levels), with an interim target to reduce 40 percent of carbon emissions by 2030 . Subsequent legislation went into effect that will fine building owners for exceeding carbon emission limits beginning this year. As a result, buildings owners will soon be forced to decarbonize their space and water heating systems to avoid these fines.
The main objective of this study is to explore various air source heat pump (ASHP) technologies and configurations that could feasibly replace fossil fuel heating and water heating systems for NYC midrise multifamily buildings using case study approach. Using insights from an existing building that recently partnered with the Association of Energy Affordability (AEA) to replace their fossil fuel heating and water heating systems with heat pumps, this report couples building energy modeling (BEM) analysis and empirical data from this case study project and other recently completed projects by AEA, to assess energy & carbon emissions savings, and installation feasibility, for retrofitting existing systems with market-ready technologies. Three ASHP technologies were selected for the space heating analysis: variable refrigerant flow (VRF) heat pumps, packaged terminal heat pumps (PTHPs), and central air-to-water heat pumps (AWHPs). This report also addresses retrofitting fossil fuel water heating systems with air source heat pump technology. Qualitative and quantitative data collected by AEA from recently completed multifamily retrofit projects are used to supplement the BEM and feasibility analysis to help guide future retrofits. The BEM analysis indicates that the three space heating ASHPs offer comparable energy and carbon emissions savings, but the feasibility of installing each technology varies greatly depending on the existing configuration of the heating and water heating systems. The analysis shows that electrifying space heating and water heating in an NYC multifamily building reduces carbon emissions by at least 80 percent and 56 percent, respectively. The recently completed projects by AEA reveal that PTHPs offer the easiest pathway to decarbonize heating in terms of the installation process but may present challenges for buildings that provide heat to their tenants via central heating systems. Based on the BEM analysis, VRF systems are the most energy efficient, but they have a high upfront cost and present the most difficult installation process for retrofitting this building type. For the buildings with central heating systems, especially those using hydronic boiler systems, AWHPs should be a strong consideration due to their ability to electrify heating while reducing the disturbance to tenants during the installation process and ongoing operation. In summary, electrification of existing multifamily buildings is highly feasible and retrofitting this sector is essential to accomplish NYCs decarbonization goals.
Recommended Citation
Chussid, Samuel, "Analysis of Energy Savings and Feasibility of Retrofitting New York City Midrise Multifamily Buildings with Air Source Heat Pump Technology" (2024). CUNY Academic Works.
https://academicworks.cuny.edu/cc_etds_theses/1297
