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© 2002,
Architectural Energy Corporation.
All Rights Reserved.
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 Funded
by California Energy Commission's Public Interest Energy
Research (PIER) Program
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P2. Night Ventilation with Building Thermal Mass > Conclusions
Conclusions:
- The night ventilation precooling strategy can be implemented using the
same sensors and control hardware employed within an economizer controller. Therefore, it should be cost effective to integrate night ventilation control with economizers for packaged equipment used in small commercial buildings. Even greater savings should be possible for packaged units that use variable speed fan control.
- If night precooling is being considered for a new design, a return air damper should be specified and controlled so that it closes during night ventilation precooling.
- Applying night ventilation precooling to existing construction will probably require retrofitting controller hardware.
Commercialization potential:
Technical integration of the precooling algorithm in new packaged units
will depend on the sophistication of the controllers offered by the manufacturers.
It is close to a no-cost addition since no additional sensors are required.
However, the addition of a return air damper and controls will probably
add as much as $300 to $500 to the price of a unit.
Recommendations:
- Conduct a market survey of available packaged units to determine the range of fan and motor efficiencies, as well as whether variable speed indoor fans are available. Building code changes should be considered to promote two-speed, or fully variable speed, fan motors.
- Publish the results of the market survey to architects, engineers, and
building managers.
- Promote designs with greater mass integrated into the interior in climate
zones where night ventilation precooling is effective.
Benefits to California:
Based on new data regarding the characteristics of California building
stock and statewide energy use, the projected benefits of this project
are updated as follows:
Updated Baseline:
This project focused on assessing the potential for night ventilation in
conjunction with use of building thermal mass for buildings with packaged
air-conditioning. The Commission data for Year 2000 shows that buildings
with packaged air-conditioners used 8,226 GWh and accounted for 4,900 MW
of peak demand.
Updated Outcome:
Assuming that nighttime ventilation may be applicable to 25% of the commercial building stock with packaged air-conditioning, this fraction would account for estimated electricity use of 2,056 GWh and 1,225 MW of peak demand. Assuming that 5% savings could be achieved, the estimated electricity savings would be 103 GWh and demand savings would be 61 MW.
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