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HVAC Energy Efficiency

Source: click here for the article as listed at Wikipedia.org

Heating energy

Water heating is more efficient for heating buildings and was the standard many years ago. Today forced air systems can double for air conditioning and are more popular. The most efficient central heating method is geothermal heating.

Energy efficiency can be improved even more in central heating systems by introducing zoned heating. This allows a more granular application of heat, similar to non-central heating systems. Zones are controlled by multiple thermostats. In water heating systems the thermostats control zone valves, and in forced air systems they control zone dampers inside the vents which selectively block the flow of air.

Air conditioning energy

The performance of vapor compression refrigeration cycles is limited by thermodynamics. These AC and heat pump devices move heat rather than convert it from one form to another, so thermal efficiencies do not appropriately describe the performance of these devices. The Coefficient-of-Performance (COP) measures performance, but this dimensionless measure has not been adopted, but rather the Energy Efficiency Ratio (EER). To more accurately describe the performance of air conditioning equipment over a typical cooling season a modified version of the EER is used, and is the Seasonal Energy Efficiency Ratio (SEER). The SEER article describes it further, and presents some economic comparisons using this useful performance measure.

HVAC Systems Design and Safety

Heating, ventilating and air-conditioning (HVAC) systems can play several roles to reduce the environmental impact of buildings. The primary function of HVAC systems is to provide healthy and comfortable interior conditions for occupants. Well-designed, efficient systems do this with minimal non-renewable energy and air and water pollutant emissions. Cooling equipment that avoids chlorofluorocarbons and hydrochlorofluorocarbons (CFCs and HCFCs) helps reduce damage to the ozone layer.

However, even the best HVAC equipment and systems cannot compensate for a building design with inherently high cooling and heating needs.^{[citation needed]} The greatest opportunities to conserve non-renewable energy are through architectural design that controls solar gain, while taking advantage of passive heating, daylighting, natural ventilation and cooling opportunities. The critical factors in mechanical systems' energy consumption - and capital cost - are reducing the cooling and heating loads they must handle.

In the 2008 Nanotech/Cleantech forum sponsored by the California Institute of Nanotechnology and the Cleantech Institute, a new type of HVAC system was unveiled by Blue Earth Energy Systems using liquid nitrogen as a coolant and combining a traditional system with a Rankine cycle turbine. The resulting system reportedly uses only 13% as much energy as a conventional HVAC chiller.[1]

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