$1.5 Million AFB Fire Station Has Solar Energy Domestic Hot Water
features
United States Air Force
A feature of the recently completed $1.2 million central fire station at Griffiss Air Force Base in New York State is a solar energy system for the domestic hot water supply. In keeping with the times, the station is heavily insulated to reduce heating costs.
The solar energy system was a flat plate collector system, a type used for many office and residential buildings. Each collector is 93 X 35 X 4 1/2 inches, totaling 570 square feet for the entire collector system.
Each collector is in a weathertight casing of bronze-anodized aluminum, which can withstand a 90-pound impact and has an expected service life of 25 years. The transparent cover is 1/8-inch tempered glass, which should not fail due to thermal cycling during winter and summer temperatures. The casing is designed to withstand winds of 90 mph.
Underground conduit
A 120-foot underground conduit runs from the solar collectors to the water storage tank in the fire station. The conduit has a 14-inch cast iron cylindrical casing. Within this is a 10-inch pipe, insulated with 1-inch-thick sectional fiberglass, that contains two 2-inch copper lines. These copper lines perform the supply and return functions between the collectors and the storage tank.
The 750-gallon vertical storage tank is made of carbon steel with a cement lining to prevent rust. The cost of this tank was $3692.
Along with the solar storage tank is a 120-gallon electric water heater. It has an automatic cut-in to the solar system and boosts the solar-heated water to the desired temperature of days lacking sunshine.
According to the contractor, maintenance of the solar system is the range of skills normally found within a maintenance organization, and the system will not require a lengthy shutdown for maintenance.
Answer to rust problem
To eliminate the possibility of rust, which has been a major headache in the past, this system will use a propylene glycol anti-freeze solution as the heat transfer fluid. The collector panels are designed to survive a zero flow, or stagnation, condition without damage.
The solar energy system cost $28,200, and according to the architect, Ed Maybeck, an energy study estimate of the savings is $39,200 for the life of the system.
The angle of the collector panels and the direction they face are among the decisions that must be made for each solar energy system. At Griffiss, the panels are set at a 53-degree angle and face due south. Studies performed in the Northeast have indicated that between 45 and 60 degrees is the optimum angle. However, the angle depends on local conditions, such as the density of trees, angle of solar rays, surrounding terrain and height of buildings. The Griffiss system has the advantage of being in a relatively open area.
The performance level expected of the solar energy collectors is for an average fluid temperature of 120 to 150°F, which is considered normal for a domestic service water heating system. The total domestic water demand is approximately 531,000 Btu per day. That figure has taken into consideration the use of a commercial dishwasher and the number of fire fighters in the station.
Station construction
The 112 X 173-foot fire station can accommodate 20 fire fighters with living and office facilities. The truck floor houses all base fire apparatus, the largest of which is a P-15 crash truck.
The single-story station has a steel frame and a metal roof with rigid roof insulation and a builtup bituminous roof covering. The roofing insulation has an R-value of 18 and is 4 1/2 inches thick.
The exterior walls are made of metal siding over gypsum sheathing and metal studs with batt insulation, aluminum windows, insulating glass and insulated sectional overhead doors. The 6-inch-thick, mineral fiber, batt insulation has a U value (heat transmission rate) of .05.
United States Air Force photos
