Reduce natural gas consumption in large commercial buildings with a path to cost-efficient solutions.
Funding Sources: California Energy Commission EPIC Funding CBE Members In-kind funding from Genentech and Price Industries
The research team will demonstrate and evaluate a package of low-cost measures to reduce natural gas consumption by commercial building heating systems — a significant source of greenhouse gas emissions. We will use the findings from field tests and data analyses to develop a web-based screening tool and a design guide to accelerate technology adoption across diverse portfolios of buildings with varied infrastructures. This approach offers a solution in terms of cost and convenience more accessible and scalable than replacing entire HVAC systems for full electrification.
Significance to Industry
Natural gas consumption for space and water heating represents two-thirds of CO2 emissions from commercial buildings. A previous CBE study of a large office building in San Mateo County revealed that with a gas-fired boiler serving hot-water reheat, only 17% of the energy cost went towards useful heating, while 83% was wasted due to piping losses and boiler inefficiency. As these are the most prevalent systems in commercial buildings, addressing these inefficiencies and losses represents a major opportunity for reducing costs and greenhouse gas emissions.
Although hot-water reheat is a predominant system installed in existing large buildings, we know of no viable solutions to decarbonize these systems without entirely replacing them. This is not feasible from a cost perspective (even at boiler and/or air handling unit end-of-life) as it effectively means replacing the entire HVAC system. This includes the HVAC terminal units serving individual rooms, and the associated disruption to occupants that modifying those would entail. However, in order to meet our climate goals, it is essential that we determine a pathway to cost-effectively reduce the carbon emissions associated with these systems.
The four central project tasks will be: (1) field testing energy-saving measures at the demonstration sites (two commercial office buildings, 120,000 and 110,000 ft2) including controls upgrades, valve replacements, and boiler replacement; (2) conducting lab testing to evaluate measures and incorporate the findings into new design guidance; (3) evaluating the scalability of our solutions across datasets of a larger portfolio of buildings; and (4) developing a screening tool, design guide and other resources for market transformation. CBE will play the lead role in the project management, technology development and evaluation, lab testing, data analysis, screening tool development and outreach activities. The upgrades related to controls will be based on ASHRAE Guideline 36-2018, ‘High-Performance Sequences of Operation for HVAC Systems.’
CBE will collaborate on this research with numerous CBE industry partners and others. CBE partner Genentech is providing two field study sites where retro-commissioning and boiler upgrades are planned, Price Industries will offer in-kind support at its HVAC testing laboratory, and CBE’s consortium members are providing additional match funding. Taylor Engineering will lead the implementation at the demonstration sites, provide expert practical technical expertise, and lead the writing of the guide. TRC will lead the installation of monitoring equipment, data acquisition, and policy recommendation tasks. The Western Cooling Efficiency Center (WCEC) at UC Davis will lead the field measurements to validate the method and assess loss pathways in more detail in the field. We will work with additional partners (such as the City of Oakland and California State University) to implement our solutions more widely following completion of the field demonstration, scalability evaluation, and development of resources for building operators.
Publications and Reports
Raftery, P., Vernon, D., Singla, R., & Nakajima, M. (2023). Measured Space Heating Hot Water Distribution Losses in Large Commercial Buildings. UC Berkeley: Center for the Built Environment. https://escholarship.org/uc/item/46h4h28q
Wendler, P., Raftery, P., & Cheng, H. (2023). Variable Air Volume Hot Water Reheat Terminal Units: Temperature Stratification, Performance at Low Hot Water Supply Temperature, and Myths from the Field. UC Berkeley: Center for the Built Environment. https://escholarship.org/uc/item/6b9590qr
Roa, C., Raftery, P., Singla, R., Pritoni, M., & Peffer, T. (2022). Detecting Passing Valves at Scale Across Different Buildings and Systems: A Brick Enabled and Mortar Tested Application. Lawrence Berkeley National Laboratory.
Lamon, E., P. Raftery, and S. Schiavon. 2022. Boiler retrofits and decarbonization in existing buildings: HVAC designer interviews. Prepared for California Energy Commission. Accepted for publication in ACEEE Summer Study on Energy Efficiency in Buildings, Panel 5. August. https://escholarship.org/uc/item/6k4369zv
Raftery, P., A. Geronazzo, H. Cheng and G. Paliaga, 2018. Quantifying energy losses in hot water reheat systems. Energy and Buildings, Nov, Vol 179, Issue 1, pp. 183-199 https://escholarship.org/uc/item/3qs8f8qx
Raftery, P., Li, S., Jin, B., Ting, M., Paliaga, G., and Cheng, H. 2018. Evaluation of a cost-responsive supply air temperature reset strategy in an office building. Energy and Buildings, 158(1), 356-370. https://escholarship.org/uc/item/1fk2m3v6 http://dx.doi.org/10.1016/j.enbuild.2017.10.017
Paliaga, G., H. Zhang, T. Hoyt and E. Arens, 2019. Eliminating Overcooling Discomfort While Saving Energy. ASHRAE Journal, April. p. 14-28. http://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_201904/index.php#/16