To demonstrate how incremental changes can conserve energy in existing buildings, the Environmental Protection Agency (EPA) highlights 1900 K Street, a 13-story government office building in Washington, D.C. Within three years, facility managers raised the energy performance score of calibrated controls, installed light motion sensors and a variable frequency drive, reprogrammed the building’s energy management system and upgraded a chiller.
As a result, the building saved $1.09 per square foot in energy costs and reports an annual CO2 emission reduction of 46 million pounds.
Older buildings bleed energy through poorly insulated walls and windows. Others require equipment upgrades to maintain a high level of energy efficiency. To keep your buildings operating as efficiently as possible, the EPA recommends five steps:
1. Analyze the Building
Mike Zatz, the market sectors group chief in the EPA’s Energy Star program, recommends an evaluation of any major building system that is more than 15 or 20 years old. Energy audits identify multiple ways to reduce operating costs by examining the HVAC system controls and building envelopes.
According to Buddy Gregory, the facilities and risk manager for the town of Castle Rock, Colo., the physical characteristics of the building, and the age, condition and energy efficiency of the various systems can affect the building’s efficiency. “The professional can determine how much energy is being used by each building system and accurately predict what it will cost to retrofit the building,” he says.
If air leaks persist, consider a blow test, which involves the use of high-powered fans and interior and exterior pressure readings. An evaluation will identify which areas need additional sealing.
2. Install More Energy-Efficient Lighting
Don’t replace your cooling unit just yet. “It is important to look at improvements to lighting and plug load before assessing and replacing large HVAC systems, like the boiler or chiller,” Zatz says. By doing so, you ensure that the correct size of equipment is installed.
According to Gregory, many older buildings are wired with energy-draining incandescent bulbs, as well as high-energy transformers, electrical distribution panels and processing equipment. “It’s often cheaper to replace the entire light fixture with one that uses compact fluorescent (CFL) or LED lighting,” he says. “Even if new light fixtures are slightly more expensive, the quick payback in energy savings can be well worth the investment.”
The installation of occupancy sensors, coupled with more efficient equipment, will lower the overall heat generated in the space, thereby reducing the net cooling load in the summer.
3. Replace or Retrofit Inefficient Equipment
“Heating, cooling and electrical systems use the bulk of the energy in older buildings,” Gregory says. But small changes to them can make a substantial difference.
For example, he was able to save his town $5,000 to $10,000 per year by replacing a 20-year-old, 1.0-million BTU boiler for the swimming pool in a recreation center with a heat exchanger that uses only 0.50-million BTUs. “Our energy costs will be cut in half,” Gregory says, “and the new heat exchanger is able to heat the water much quicker and can maintain more consistent water temperatures than the old boiler.”
When boiler replacement isn’t feasible, insulating hot-water distribution lines and installing a combustion monitoring and control system to trim excess air are options.
4. Improve Insulation
If buildings aren’t maintained as they age, doors that lose energy through the air spaces around the frame, as well as drafty single-pane windows, might need to be replaced.
Gregory says, “Sealing off air leaks around windows, doors and electrical outlets provides a quick, inexpensive way to get an immediate payback on energy and cost savings.”
If the rooftop is the biggest source of leakage, consider adding rigid board insulation next to the outside surface of the roof or fiberglass batts inside the roof or to attic floors.
Also, there are numerous ways to insulate existing windows. Window films can be retrofitted — and can be applied directly to the interior surfaces of all types of glass — to reduce heat gain from solar radiation. Adding window films saves energy by improving the balance of heating and cooling systems and allowing HVAC downsizing.
5. Implement Energy Saving Campaigns
“We believe that most buildings can achieve at least a 10 percent reduction in energy use,” Zatz says, “largely through behavioral changes and operations and maintenance improvements.”
Gregory implemented a public awareness campaign for less than $5,000 that yielded $62,000 in savings within nine months. Stickers placed on all light switches and posters in key locations reminded people to turn off lights, computers and appliances they weren’t using. “We also changed to digital programmable thermostats and implemented new energy conservation indoor temperature standards for heating and cooling seasons,” he says.
Instead of imposing new regulations, Gregory thought the program would be more effective if participation was voluntary, and the decision seems to have paid off.
Be sure to join the Lowe’s ProServices LinkedIn Group to read additional content and interact with other Construction/Trade and MRO professionals.