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.

IBM’s new offices at Dulles Station West in Herndon, Va., utilized Petersen’s PAC-1000 F Flush Series column covers. The columns are within the office’s Mobility Area, which is designed for a mobile workforce looking for quick in-and-out work space. The majority of workspaces in the office are unassigned and intended to be used on a temporary basis.

| Dec 6, 2010

Honeywell survey

Rising energy costs and a tough economic climate have forced the nation’s school districts to defer facility maintenance and delay construction projects, but they have also encouraged districts to pursue green initiatives, according to Honeywell’s second annual “School Energy and Environment Survey.”

| Dec 2, 2010

GKV Architects wins best guest room design award for Park Hyatt Istanbul

Gerner Kronick + Valcarcel, Architects, PC won the prestigious Gold Key Award for Excellence in Hospitality Design for best guest room, Park Hyatt Macka Palas, Istanbul, Turkey. Park Hyatt Maçka Palace marries historic and exotic elements with modern and luxurious, creating a unique space perpetuating Istanbul’s current culture. In addition to the façade restoration, GKV Architects designed 85 guestrooms, five penthouse suites, an ultra-hip rooftop bar, and a first-of-its-kind for Istanbul – a steakhouse, for the luxury hotel.

| Dec 2, 2010

U.S Energy Secretary Chu announces $21 Million to improve energy use in commercial buildings

U.S. Energy Secretary Steven Chu announced that 24 projects are receiving a total of $21 million in technical assistance to dramatically reduce the energy used in their commercial buildings. This initiative will connect commercial building owners and operators with multidisciplinary teams including researchers at DOE's National Laboratories and private sector building experts. The teams will design, construct, measure, and test low-energy building plans, and will help accelerate the deployment of cost-effective energy-saving measures in commercial buildings across the United States.

| Dec 1, 2010

The long road to Revit on the Mac begins

| Nov 29, 2010

Data Centers: Keeping Energy, Security in Check

Power consumption for data centers doubled from 2000 and 2006, and it is anticipated to double again by 2011, making these mission-critical facilities the nation’s largest commercial user of electric power. Major technology companies, notably Hewlett-Packard, Cisco Systems, and International Business Machines, are investing heavily in new data centers. HP, which acquired technology services provider EDS in 2008, announced in June that it would be closing many of its older data centers and would be building new, more highly optimized centers around the world.

| Nov 29, 2010

New Design Concepts for Elementary and Secondary Schools

Hard hit by the economy, new construction in the K-12 sector has slowed considerably over the past year. Yet innovation has continued, along with renovations and expansions. Today, Building Teams are showing a keener focus on sustainable design, as well as ways to improve indoor environmental quality (IEQ), daylighting, and low-maintenance finishes such as flooring.

| Nov 29, 2010

Renovating for Sustainability

Motivated by the prospect of increased property values, reduced utility bills, and an interest in jumping on the sustainability bandwagon, a noted upturn in green building upgrades is helping designers and real estate developers stay busy while waiting for the economy to recover. In fact, many of the larger property management outfits have set up teams to undertake projects seeking LEED for Existing Buildings: Operations & Maintenance (LEED-EBOM, also referred to as LEED-EB), a certification by the U.S. Green Building Council.

| Nov 23, 2010

The George W. Bush Presidential Center, which will house the former president’s library

The George W. Bush Presidential Center, which will house the former president’s library and museum, plus the Bush Institute, is aiming for LEED Platinum. The 226,565-sf center, located at Southern Methodist University, in Dallas, was designed by architect Robert A.M. Stern and landscape architect Michael Van Valkenburgh.

| Nov 23, 2010

Honeywell's School Energy and Environment Survey: 68% of districts delayed or eliminated improvements because of economy

Results of Honeywell's second annual “School Energy and Environment Survey” reveal that almost 90% of school leaders see a direct link between the quality and performance of school facilities, and student achievement. However, districts face several obstacles when it comes to keeping their buildings up to date and well maintained. For example, 68% of school districts have either delayed or eliminated building improvements in response to the economic downturn.

Currently Reading

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

Tags

| Dec 7, 2010

| Dec 6, 2010

| Dec 2, 2010

| Dec 2, 2010

| Dec 1, 2010

| Nov 29, 2010

| Nov 29, 2010

| Nov 29, 2010

| Nov 23, 2010

| Nov 23, 2010

Most Popular Content

Magazine Subscription

Get our Newsletters

Follow BD+C: