By Herbert Schwind, PE, CEM, CFM, LEED AP O + M
OWNER: Town of Glastonbury, Conn., Facilities Services Department
PROJECT: Firehouse heating-system replacement
ENERGY CONSULTING FIRM: Celtic Energy; Glastonbury, Conn.
SYSTEM DESIGN: Bemis Associates LLC; Newington, Conn.
DESIGN, HAZARDOUS MATERIAL ABATEMENT, AND CONSTRUCTION: $88,500
FUNDING: Energy Efficiency & Conservation Block Grant ($46,700); utility company incentive payments ($6,200)
AVERAGE ANNUAL ENERGY SAVINGS: $10,000
If you're skeptical about efficiency claims regarding radiant heaters and condensing boilers, you're not alone. Recent experience, however, has turned this skeptic into a believer.
The Town of Glastonbury is a municipality of 35,000 citizens occupying more than 52 square miles of central Connecticut, very near Hartford. Our New England climate translates into approximately 6,000 heating degree days per calendar year.
Because we've had an aggressive energy management program over the years, much of the low-hanging fruit related to facilities — lighting change-outs, installing occupancy-sensing light controls and vending machine controllers, retro-commissioning HVAC systems, and installing a server-based computer control system — had been implemented. So a few years ago, we hired a consulting firm to audit our larger buildings for additional efficiency measures.
One recommendation was to install radiant heaters in the equipment bays of our firehouses, an improvement that would reduce natural gas consumption by an estimated 30%.
Unlike gas-powered convection heat, which warms air, radiant heaters transfer energy directly from an emitting heat source to people and objects within a space, warming them without heating the air. Radiant heat involves the transfer of energy through space by electromagnetic radiation; the most common example is heat from the sun.
Because of our relatively large geographic size, Glastonbury has four firehouses located throughout the community. Three are served by natural gas. They range from 6,400 to 8,850 square feet with the equipment bays making up about 50% to 60% of that area. The facilities are 20 to 40 years old and the heating systems in all of them are original.
All have hot water heating systems that rely on convection heating. The equipment bays have ceiling-hung unit heaters which heat and circulate the air within the space; administrative spaces have baseboard or other convection-type heat. The equipment bay doors are equipped with sensors that stop the heaters when open. Even so, much of the heated air escapes whenever the doors open and the facility's boiler has to replenish the loss.
Almost all of the natural gas usage is attributable to heating with only small, non-heating, gas loads associated with domestic hot water and a small kitchen function contributing to the total gas usage.
We decided to use radiant heat in the bay of the largest and oldest firehouse: 40 years old and 8,850 square feet. Because it'd eliminate the burden of heating almost half the facility's square footage, we'd be able to replace the gas-fired, hot water boiler rated at 910 MBH with a newer, smaller, and more efficient condensing boiler. (One MBH equals 1,000 BTUs per hour.) Under the proper conditions, condensing boilers achieve higher efficiency than conventional boilers by condensing the steam found in the waste gases of combustion, which conventional boilers exhaust. Condensing that water vapor extracts the latent heat present, enhancing efficiency.
We'd use U.S. EPA's ENERGY STAR Portfolio Manager, which we've been using since 2007, to evaluate the new system's performance and decide if similar retrofits in other firehouses would be beneficial.
The old boiler was removed at the end of the 2009/2010 heating season and replaced with a condensing boiler rated at roughly half the size (see caption on page 69). We installed two Combustion Research Corp. Reflect-O-Ray EDS 4 vacuum-exhausted radiant heaters, each with three burners and one exhaust. The units were suspended from the ceiling and exhausted through the exterior wall.
The new system began operating in January 2010 and has been such a success that we're retrofitting our other two firehouses that are heated with natural gas.
Heating fuel usage fell by more than 40% with each of the two measures — radiant heaters and the higher-efficiency boiler — contributing about equally to the savings. Our town also is avoiding 20 metric tons of carbon dioxide equivalent emissions each year.
We've realized non-energy-related benefits as well.
We haven't had any complaints from occupants or users regarding their comfort or work environment. In fact, the old boiler had asbestos-containing materials in the gasketing and fittings. Its demolition was performed as a hazardous material abatement, eliminating a safety and management concern. The new boiler is remarkably small, so servicing technicians appreciate the additional work room now available in a typically cramped mechanical space.
While firehouses are relatively small in scale, similar benefits can be expected in larger applications — fire departments, warehouses, and highway equipment garages, for example — that have open equipment or material storage and servicing areas.
—Schwind (email@example.com) is facilities director for the Town of Glastonbury, Conn. In addition to 25 years as a U.S. Navy Civil Engineer Corps officer, he's a U.S. Green Building Council LEED-Accredited Professional, an Association of Energy Engineers Certified Energy Manager, and an International Facilities Management Association Certified Facilities Manager.