Report: HVAC occupancy sensors could slash building energy demand by 18%

A single advanced building control now in development could slash 18 percent — tens of thousands of dollars — off the overall annual energy bill of the average large office building, with no loss of comfort, according to a report by researchers at the Department of Energy's Pacific Northwest National Laboratory.

"An 18-percent boost in building energy efficiency by modifying a single factor is very, very good," said team leader Michael Brambley. "The savings were much greater than we expected."

The report is based on extensive simulations of the impact of one type of advanced building control now in the offing in the building industry. The device is capable of customizing the level of ventilation by sensing the number of people in different areas or zones of a building and then adjusting fan speed and air movement accordingly.

That's a big change from the way most sensor-based ventilation systems operate now: Currently, if there is even a single person in a room, ventilation runs full blast, as if the room is full.

But a room with just a few people doesn't need nearly as much ventilation as a crowded room. Why have a fan pushing around air for ventilation for 100 people if there's only one individual in the room? It's like airing out your house completely because there's one small whiff of bacon still in the kitchen.

"This is the reason you often feel cold when you're in a big space like a conference room or cafeteria without a lot of people," said engineer Guopeng Liu, the lead author of the report. "Technology available today doesn't detect how many people are in a room, and so air flow is at maximum capacity nearly constantly. That creates a big demand to re-heat the air before it enters the rooms. It takes a lot of energy to keep you comfortable under those circumstances."

Current occupancy sensors have helped the nation save significant amounts of energy by automatically turning off lights when they're not needed. But the team estimates that the more advanced versions still to come — which count the number of people in rooms — will save approximately 28 times as much energy, when used both for lighting and ventilation, compared to current sensors.

The project began three years ago when Liu began exploring the idea of adjusting air flow to different zones of a building based on the precise number of people in a room. That "decision" of how much air to move takes place in a piece of equipment known as a variable air volume terminal box. The new sensors that count people are likely to become available within the next few years. While they are currently very expensive, the technology is improving rapidly and the cost is expected to come down, Brambley noted.

"We undertook this study to try to determine if this is a technology worth pursuing vigorously. The answer, clearly, is yes. Using the number of people in a room as a factor in determining the level of air flow offers great promise for saving energy and money," said Brambley.

To do its study, the team focused on a prototypical large commercial office building whose footprint is 160 feet by 240 feet — about 80 percent the size of a football field. The model building is 12 stories and also has a basement, giving it a total of about 500,000 square feet. Such buildings in the United States take up more than 4.4 billion square feet. To visualize the size, think of the land area covered by Seattle — and a little bit of its suburbs — as a giant one-story building.

Brambley's team programmed the simulation to heat a building if temperatures dipped below 70 degrees Fahrenheit and to provide cooling at temperatures beginning at 75 degrees. Numbers were set back 10 degrees on the evenings and weekends. Occupancy patterns were estimated based on past studies.

In 13 of the nation's 15 climate regions, the PNNL team estimates that the advanced controls would save at least $40,000 annually for each building similar in size to the one modeled in the study. In two cities, Baltimore and Fairbanks, the savings stretch to more than $100,000 each year, because of the greatly reduced need to heat new air being pumped in from the cold outdoors. Even in the two cities where the savings would be the least, El Paso and Miami, estimated savings come to $33,400 and $23,500, respectively.

"While buildings have gotten much more efficient in the last two decades, there are still huge gains to be had," noted Brambley.

Since just a small percentage of office buildings in any given year are newly built, Brambley and Liu say a prime target for these advanced controls is retrofitting existing buildings. Liu notes that technology has leaped forward since 1989 — the year the average large office building was built - offering huge energy gains even with the expense of retrofitting.

Since heating and cooling and related equipment usually draw much more energy than lighting, those systems offer a greater opportunity for savings. The team found that advanced controls for ventilation offer about eight times as much savings as advanced controls for lighting, where lights are turned off more quickly than is now common after everyone leaves a room. When the HVAC (heating, ventilation, and air conditioning) system alone is considered, the advanced controls cut energy usage by nearly 40 percent.

A stumbling block to the new technology is that certain advanced controls might require modification to some building codes. For instance, current codes require some ventilation at all times no matter how many people are present. Brambley thinks the options are worth considering, given the energy savings at stake.

In addition to Brambley and Liu, mechanical engineer Jian Zhang and engineer Robert Lutes contributed to the project. The work was support by DOE's Office of Energy Efficiency and Renewable Energy.

Incentivizing, rather than mandating the return to the office, is the key to bringing back happy employees that want to work from the office. Spaces that are designed and curated for human-centric experiences will attract employees back into the workplace, and in turn, make office buildings thrive once again. Perkins&Will’s Wyatt Frantom offers a macro to micro view of the office market and the impact of employees on the future of work.

Healthcare Facilities | Jul 19, 2023

World’s first prefab operating room with fully automated disinfection technology opens in New York

The first prefabricated operating room in the world with fully automated disinfection technology opened recently at the University of Rochester Medicine Orthopedics Surgery Center in Henrietta, N.Y. The facility, developed in a former Sears store, features a system designed by Synergy Med, called Clean Cube, that had never been applied to an operating space before. The components of the Clean Cube operating room were custom premanufactured and then shipped to the site to be assembled.

Performing Arts Centers | Jul 18, 2023

Perelman Performing Arts Center will soon open at Ground Zero

In September, New York City will open a new performing arts center in Lower Manhattan, two decades after the master plan for Ground Zero called for a cultural component there. At a cost of $500 million, including $130 million donated by former mayor Michael R. Bloomberg, the Perelman Performing Arts Center (dubbed PAC NYC) is a 138-foot-tall cube-shaped building that glows at night.

Codes and Standards | Jul 17, 2023

Outdated federal rainfall analysis impacting infrastructure projects, flood insurance

Severe rainstorms, sometimes described as “atmospheric rivers” or “torrential thunderstorms,” are making the concept of a “1-in-100-year flood event” obsolete, according to a report from First Street Foundation, an organization focused on weather risk research.

Multifamily Housing | Jul 13, 2023

Walkable neighborhoods encourage stronger sense of community

Adults who live in walkable neighborhoods are more likely to interact with their neighbors and have a stronger sense of community than people who live in car-dependent communities, according to a report by the Herbert Wertheim School of Public Health and Human Longevity Science at University of California San Diego.

Sustainability | Jul 13, 2023

Deep green retrofits: Updating old buildings to new sustainability standards

HOK’s David Weatherhead and Atenor’s Eoin Conroy discuss the challenges and opportunities of refurbishing old buildings to meet modern-day sustainability standards.

Contractors | Jul 13, 2023

Construction input prices remain unchanged in June, inflation slowing

Construction input prices remained unchanged in June compared to the previous month, according to an Associated Builders and Contractors analysis of U.S. Bureau of Labor Statistics Producer Price Index data released today. Nonresidential construction input prices were also unchanged for the month.

U.S. Embassy in Ankara, Turkey, designed by Ennead Architects Photo: Scott Frances

Government Buildings | Jul 13, 2023

The recently opened U.S. Embassy in Ankara reflects U.S. values while honoring Turkish architecture

The U.S. Department of State’s Bureau of Overseas Buildings Operations (OBO) has recently opened the U.S. Embassy in Ankara, Turkey. The design by Ennead Architects aims to balance transparency and openness with security, according to a press statement. The design also seeks both to honor Turkey’s architectural traditions and to meet OBO’s goals of sustainability, resiliency, and stewardship.

Currently Reading

Report: HVAC occupancy sensors could slash building energy demand by 18%

Tags

Market Data | Jul 24, 2023

Hotel Facilities | Jul 21, 2023

Office Buildings | Jul 20, 2023

Healthcare Facilities | Jul 19, 2023

Performing Arts Centers | Jul 18, 2023

Codes and Standards | Jul 17, 2023

Multifamily Housing | Jul 13, 2023

Sustainability | Jul 13, 2023

Contractors | Jul 13, 2023

Government Buildings | Jul 13, 2023

Most Popular Content

Magazine Subscription

Get our Newsletters

Follow BD+C: