UFC 3-420-01
25 October 2004
506.2 Life cycle cost analysis. Executive Order 13123, Greening the
Government Through Efficient Energy Management requires life cycle cost
analysis (LCCA) of alternatives and maximum utilization of energy conserving
methods and equipment. Evaluate alternative energy source options, such as
electric, steam, oil-fired, and gas-fired service water heater. Evaluate SWH
storage tank capacity and electric heater element sizing to minimize electric
demand charges to the government. Larger storage tanks with smaller heater
elements may be cost effective due to reduced demand charges, although the
longer storage recovery time and the additional costs for providing non-standard
tank and element selections should also be considered. Do not exceed the
ASHRAE recommended 8-hour maximum recovery time. Also consider the
incremental cost of additional electric service capacity versus the incremental
costs of providing steam or gas service or providing fuel oil storage and delivery.
Include the costs of providing combustion air and flue gas exhaust for fuel-fired
water heaters. Do not consider the cost of the tempering valve in the life cycle
costs analysis, it is required by the 140F (60C) storage temperature to avoid
legionella. However, since it is required, consider the life cycle cost advantages
of storing hot water at higher temperatures, if the source is electric, steam, or
natural gas, and the tank insulation is increased to maintain equal total heat loss.
A smaller SWH storage tank may reduce the size of the mechanical room and
the building, which will reduce the energy and capital costs of the facility.
Consider a pre-heat tank upstream of the SHW storage tank for applications
recovering heat from refrigerant hot gas, steam condensate, process waste
cooling, solar collectors, and diesel engines. Provide a tempering valve for all
heat recovery SWH systems to limit the supply temperature, because the
recovered heat can heat the storage tank above the normal storage temperature.
A pre-heat tank may increase the amount of heat usably recovered prior to
allowing the water to be heated by prime energy. Consider sealed combustion
chambers for natural gas-fired SWH's, with combustion air ducted directly from
and flue gases ducted directly to the outside air. This may reduce the possibility
of carbon monoxide poisoning within the occupied spaces. Ensure adequate
clearances of inlet and outlet during snow, icing, flood, and heavy wind-driven
rain conditions."
IPC CHAPTER 6 "WATER SUPPLY AND DISTRIBUTION" SUPPLEMENTS.
A.
Add "SECTION 601.5 Storage tank materials. Storage tanks will be
constructed of one of the following combinations of materials and methods: (1) Ferrous
metals lined with nonferrous metals and provided with cathodic protection. (2) Ferrous
metals lined with glass and provided with cathodic protection. (3) Ferrous metals lined
with cement and provided with cathodic protection. (4) Fiberglass reinforced plastic for
atmospheric pressure applications.
B.
Add "SECTION 602.2.1 Non-potable water exception. A non-potable
water supply, when used in an entirely separate system and when approved by the local
A-14
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