Solar Energy Units and Fire Safety
With the increased emphasis on energy conservation and the high cost of normal energy sources, everyone is looking at alternative energy sources, including solar energy utilization. Although the use of solar energy is not new, its sudden application surge is, and it may or may not cause problems in relation to fire prevention and protection.
Possibly the greatest concern relating to fire protection is the collector, which is now becoming part of the building. Solar collectors and the balance of the solar energy systems are being used for water heating, space heating (air), and heating and cooling systems.
Solar energy systems are being installed in many types of commercial and residential buldings in the United States. Solar systems have been installed in at least two fire stations, schools, an office building, in industrial laundry, an industrial complex, a restaurant, a recreation center and a medical clinic, as well as in apartment buildings, condominiums and onefamily houses.
System simple in design
A solar energy system is essentially simple insofar as the basic compounds are concerned. The primary part of the system is the collector, which has two basic configurations: flat-plate and concentrating (high temperature).
A flat-plate collector is suitable for use with either a liquid (usually water or water and antifreeze) or air. The collector may be glazed or unglazed (pool heating) and the glazing is usually heavy glass, a thermoplastic sheet or plastic film. The balance of the collector is made of copper, aluminum or a combination of both for the interior piping and heat transfer surface (absorber plate). Beneath the absorber plate is a layer of insulation, usually fiberglass, and the outside of the collector is either aluminum or a variety of thermoplastics or fiberglass resin.
The concentrating collector is essentially a trough configuration with tubing for the liquid suspended in the center of the trough. The concentrating collector is used when tracking of the sun is needed and has been used mostly in commercial buildings.
Collectors mounted on roof
Both the flat-plate and concentrating collectors are mounted in interconnected arrays of two or more collectors, depending on the system’s energy needs. The collectors are usually mounted on the roof, facing south, and in new construction, flat-plate collectors may be built into the roof.
When installed on existing buildings, collectors are mounted either directly on the roof or on supports. In the case of tracking-type concentrating collectors, the supports are vital to permit movement of the collectors as they track the sun.
The heat transfer media passes through the collectors and then goes to a storage area (tank or rock bin) or heat exchanger, or is ducted directly into the building for space heating.
There are some systems that use media which may present a toxicity or flammability problem. These media should be handled in the same manner as any other hazardous substance in regard to storage and use.
Other components of a solar utilization system include pumps, valves, and piping, which vary with the function and design of the system. All system designs and components should conform with recognized standards and codes relating to solar energy and building construction.
There are really few standards directly applicable to solar utilization at this time, although many have been proposed. The essential national resi dential standards are the product of the Department of Housing and Urban Development. HUD promulgated the “Intermediate Minimum Property Standards Supplement Solar Heating and Domestic Hot Water Systems,” No. 49:10.2, which applies to all forms of residential occupancies as well as caretype housing.
The National Bureau of Standards produced the “Interim Performance Criteria for Solar Heating and Cooling Systems in Commercial Buildings.”
Both documents rely on nationally recognized standards, such as those produced by ASTM, ANSI, NFPA and testing laboratories such as UL and FM. Most of the standards used refer to cosntruction and heat-producing installations, which relate to fire safety.
Solar energy code
Insofar as codes are concerned, the “Uniform Solar Energy Code,” published by the International Association of Plumbing and Mechanical Officials is the only code thus far, and it is designed to be used as a companion to the “Uniform Building Code.” Of course, the applicable building construction, electrical and plumbing codes are also used in checking solar energy utilization systems.
Few states have developed any specific standards at this time. Florida does have some that apply to the performance of collectors, and the California Energy Conservation and Development Commission is in the process of developing standards for components and systems as well as criteria for approved testing laboratories for solar components.
Although much of the material contained in the standards is aimed at performance and reliability, there are sections and areas of concern relating to fire prevention, protection and safety. The areas of concern are those relating to building construction and system components.
Fire safety concerns
Within the building construction segment we find the same concerns that apply to any system contained in a building. For example, all penetrations of fire-rated assemblies should be protected, and fire stopping is required if any component, such as a collector, is installed in a construction assembly that requires fire stopping. The system or any of its components should not obstruct emergency access or egress or present a hazard to required exitways.
The installation of collectors on roofs should not reduce or impair any required fire-resistivity of the roof covering. In addition, protection to prevent autoignition of combustible materials should be provided. In most instances, the collector will be mounted in such a manner as to provide air space between it and combustible surfaces.
Since many solar energy utilization systems use pumps and the system operates under pressure, the standards call for suitable automatic pressure relief devices and require that all main shutoff and control valves be well marked and readily accessible.
Any toxic or flammable liquids, or fluids that may require special handling (transfer media other than water) used in a system must conform to the appropriate standards (e.g., NFPA No. 30, “Flammable and Combustible Liquids Code”). In addition, liquids used in solar-powered equipment shall not be heated to temperatures greater than 100°F below their flash points under either no-flow or operating conditions.
Any heated components, such as heat exchangers or storage tanks, are required to have an adequate air space or surface protection to prevent injury to humans and to prevent ignition of combustibles.
Relating to fire fighting, the greatest concern is the addition of weight to a roof and the use of materials subject to melting or high smoke production, such as certain plastic components. Also, glass glazing could lend to injuries when broken and the roof obstructions could cause difficulty in ventilating during a fire. However, with proper pre-fire planning, these hazards can be minimized.
In my opinion, the application of solar utilization systems does not present any greater problems than any other heating installation. Perhaps the use of solar energy will some day reduce some of the fire problems caused by appliances now used for heating and cooling. It would be difficult to have a garage fire caused by a hot water heater pilot light if the water were heated by solar energy.
The problems with solar applications will not come from the systems, but from our usual source of fire problems— improper installation, poor maintenance and misuse of the system. However, with proper plan checking, inspection, enforcement and pre-fire planning, the problems with solar systems can be reduced to an acceptable limit.
