Analyzing Energy Conservation Measures in Different Buildings, Climate Zones
From ASHRAE Journal Newsletter, January 9, 2018
By Mary Kate McGowan, Associate Editor, News
A total of 15,840 building simulations is what it took for Zheng O’Neill, Ph.D., P.E., Member ASHRAE, and three of her graduate research assistants to collect data on 19 different energy conservation measures (ECMs) in 16 climate zones for 11 different commercial building types in the U.S.–all in hopes of finding more ways to improve commercial building energy performance.
O’Neill; Defeng Qian, Student Member ASHRAE; Yanfei Li, Student Member ASHRAE; and Fuxin Niu, Student Member ASHRAE, all of the University of Alabama, are scheduled to present the “Nationwide Savings Analysis of A Variety of Energy Conservation Measures” during a conference paper session at the 2018 ASHRAE Winter Conference.
The team concluded ECMs were more effective in extreme weather conditions.
“Climate has a large impact on EUIs [energy use intensity],” said O’Neill.
Some ECMs produce better energy savings, depending on the climate, but ECMs such as lighting power density and highly efficient envelopes tend to work well in most climate zones.
O’Neill said building envelopes are effective in colder climates as they help reduce energy consumption in a building. Whereas, energy-efficient HVAC equipment like geothermal systems could yield positive results in warmer climates.
“If you have energy–efficient equipment, which can better handle humidity control, then you probably can have a bigger advantage,” she said.
BASICS
The team used EnergyPlus, a whole building simulation program, to simulate and evaluate energy savings potentials for several ECMs, according to O’Neill. The baselines were based on ANSI/ASHRAE/IES Standard 90.1–2010, Energy Standard for Buildings Except Low-Rise Residential Buildings.
Those ECMs in the study were:
- Building Envelope
- Enhanced Building Envelope
- Glazing System Performance
- Enhanced Glazing System Performance
- Daylighting
- Enhanced Requirements for Lighting Power Density
- Lighting Controls
- Premium Package Rooftop HVAC
- Lighting Power Density
- Energy Recovery Ventilation (ERV)
- Exterior Lighting Efficiency
- Demand Control Ventilation (DCV)
- HVAC System Efficiency
- Comprehensive Measures
- Economizer
- Fan Power Reduction
- HVAC Controls
- HVAC – Fault Detection and Diagnostics (FDD)
- Water Heating
The 11 different building types were commercial prototype building models such as a hospital, medium office, small office, outpatient health-care facility, fast food restaurant, sit down restaurant, stand-alone retail store, strip mall retail store, primary school, secondary school and warehouse, according to the report. Pacific Northwest National Laboratory researchers defined the building prototypes, which are supposed to represent a majority of new buildings in the U.S.
The buildings were located in the following ASHRAE climate zones:
- 1A (Honolulu)
- 2A (Tampa, Fla.)
- 2B (Tucson, Ariz.)
- 3A (Atlanta.)
- 3B (El Paso, Texas)
- 3C (San Diego)
- 4A (New York City)
- 4B (Albuquerque, N.M.)
- 4C (Seattle)
- 5A (Buffalo, N.Y.)
- 5B (Aurora, Colo.)
- 5C (Port Angeles, Wash.
- 6A (Rochester, Minn.)
- 6B (Great Falls, Mont.)
- 7 (International Falls, Minn.)
- 8 (Fairbanks, Ala.)
The team calculated ECMs separately, but there is a trade-off of energy savings and use when different systems are working together in the same building, O’Neill said. If a building has an energy-efficient building envelope and energy-efficient HVAC equipment, that building will see combined impact from two ECMs, she said.
“You cannot actually access the EUI just by looking at a single system in a building because a building is complicated with a lot of subsystems,” O’Neill said.
FINDINGS
The team ran the simulations and analyzed the data to provide information for building designers of new and existing buildings. The report concluded with five considerations.
- Improving the performance of building envelope, fenestration assemblies and HVAC systems would have a positive influence on both electricity use intensity and gas use intensity (GUI).
- ECMs were more effective in extreme weather conditions.
- Fault detection and diagnostics could help each building.
- For a specific building, the savings number would differ based on individual building characteristics, so the report could provide some design and operation guidelines on a larger scale.
- The measures’ feasibility from the simulation-based analysis depends on the actual design and retrofit requirements.
The team also found that moist climate zones had the largest EUI savings compared to the dry and marine–excluding the Tampa, Fla., site–climate zones, according to the report. The researchers credited a gas use reduction for the humidity control as the mostly likely reason for the savings.
According to the report, ECMs in climate zones such as Hawaii, Minn., and Alaska yielded improved building envelope performance, and occupancy-based control helped reduce energy consumption in buildings
“The building load at extreme weather conditions would be relatively higher than the intermediate weather conditions, which explains why more savings occurred at the extreme weather conditions,” according to the report.
Also in those extreme climate zones, the HVAC systems dehumidify as well as maintain the room temperature around the setpoints. HVAC systems in a moist area consume more energy than dry areas, the report concludes.
BEYOND SCIENCE
Li and Quian both said participating in the study helped them academically as they prepare for careers after graduation.
Li said he now better understands the bigger picture of how different energy-efficiency measures apply to different buildings in different climate zones.
For Quian, learning the EnergyPlus software was beneficial during his first year in graduate school.
“For me, I didn’t have much experience with it before this project. We have more experience on the software [now],” he said.
In addition to the technical experience, Quian said working with the team helped teach him better ways to work with a group of other researchers.
The research team would like to thank Sean Denniston, a senior project manager at New Buildings Institute, for his support. In addition, technical support from Bing Liu, Member ASHRAE; Jian Zhang, Member ASHRAE; and Rahul Athalye, Associate Member ASHRAE, at Pacific Northwest National Laboratory’s Building Energy Regulatory Analysis Group is greatly appreciated.