This paper describes a gas-energised cold air-water HVAC system that uses a desiccant plus 50 deg F chilled water to produce 40 deg F air. The system was developed to provide a cost-effective alternative to an electric-powered cold all-air system. The 40 deg F gas air-water system is compared with a 40 deg F all-air ice thermal storage system and a conventional 55 deg F all-air system in terms of peak refrigeration requirement, primary air distribution, fan demand (primary and secondary), system peak demand (summer/winter), annual electric energy use (on/off-peak), gas input, annual demand cost, annual electric use cost, annual gas cost, total annual energy cost, and system first cost. Also presented is the impact of various utility rate structures on the energy cost of the three HVAC systems being compared. The comparative information is drawn from two studies based on a six-story, 159,000 square ft office building in northern New Jersey.

KEYWORDS: gas consumption, peak load, electricity consumption, tariffs, offices, multistorey buildings, fans, desiccants, heating, ventilation, air conditioning, gas fired, ice storage, energy storage, energy consumption, comparing, costs, USA.