The energy crisis of the mid 1970’s gave birth to a
movement to conserve energy. Over the ensuing years
much has been done to reduce the energy consumption
of new and existing buildings. Lighting efficiency has
improved so much that today we use ½ the wattage
without sacrificing lumens. Improved construction
methods, better insulation and high efficiency windows
have also helped reduce energy consumption.
However, all of these measures have resulted in a
reduction of Sensible heat gains while Latent heat gains
This section describes heating, ventilating, and air
conditioning (HVAC) systems and discusses characteristics and
components of automatic control systems. Cross-references
are made to sections that provide more detailed information.
A correctly designed HVAC control system can provide a
comfortable environment for occupants, optimize energy cost
and consumption, improve employee productivity, facilitate
efficient manufacturing, control smoke in the event of a fire,
and support the operation of computer and telecommunications
How Direct Expansion Air-Conditioning Achieves Performance Goals For most of the A / C market, refrigeration-based ( DX ) cooling is the standard, and provides a point of comparison for new technologies. To describe the benefits and improvements of DEVap A / C technology, we must discuss standard A / C. Standard A / C reacts to SHR by cooling the air sensibly and, if dehumidification is required, by cooling the air below the dew point.