Laboratories for the 21st Century: Best Practices; Energy Recovery in Laboratory Facilities (Brochure)

National Renewable Energy Laboratory (U.S.)

关键词: Working Days Ashrae;    High-Performance Buildings;    Integrated Applications;    Heating;    Sustainable Buildings;   

DOI  :  10.2172/1045090
RP-ID  :  DOE/GO-102012-3503
RP-ID  :  AC36-08GO28308
RP-ID  :  1045090

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来源: UNT Digital Library

【 摘 要 】

This guide regarding energy recovery is one in a series on best practices for laboratories. It was produced by Laboratories for the 21st Century ('Labs 21'), a joint program of the U.S. Environmental Protection Agency and the U.S. Department of Energy. Laboratories typically require 100% outside air for ventilation at higher rates than other commercial buildings. Minimum ventilation is typically provided at air change per hour (ACH) rates in accordance with codes and adopted design standards including Occupational Safety and Health Administration (OSHA) Standard 1910.1450 (4 to 12 ACH - non-mandatory) or the 2011 American Society of Heating, Refrigerating and Air Conditioning Engineers (ASHRAE) Applications Handbook, Chapter 16 - Laboratories (6 to 12 ACH). While OSHA states this minimum ventilation rate 'should not be relied on for protection from toxic substances released into the laboratory' it specifically indicates that it is intended to 'provide a source of air for breathing and for input to local ventilation devices (e.g., chemical fume hoods or exhausted bio-safety cabinets), to ensure that laboratory air is continually replaced preventing the increase of air concentrations of toxic substances during the working day, direct air flow into the laboratory from non-laboratory areas and out to the exterior of the building.' The heating and cooling energy needed to condition and move this outside air can be 5 to 10 times greater than the amount of energy used in most office buildings. In addition, when the required ventilation rate exceeds the airflow needed to meet the cooling load in low-load laboratories, additional heating energy may be expended to reheat dehumidified supply air from the supply air condition to prevent over cooling. In addition to these low-load laboratories, reheat may also be required in adjacent spaces such as corridors that provide makeup air to replace air being pulled into negative-pressure laboratories. Various types of energy recovery devices and systems can substantially reduce heating and cooling energy required for conditioning spaces in laboratories. Heating and cooling systems can be downsized when energy recovery is used because these systems reduce peak heating and cooling requirements. Heating and cooling systems can also be downsized by capturing heat generated in high-load spaces and transferring it to spaces requiring reheat. There are many opportunities for energy recovery in laboratories. This guide includes descriptions of several air-to-air energy recovery devices and methods, such as using enthalpy wheels (Figure 1), heat pipes, or run-around loops in new construction. These devices generally recover energy from exhaust air. This recovered energy is used to precondition supply air during both cooling and heating modes of operation. In addition to air-to-air energy recovery options, this guide includes a description of a water-to-water heat recovery system that collects heat from high-load spaces and transfers it to spaces that require reheat. While air-to-air recovery devices provide significant energy reduction, in some laboratory facilities the amount of energy available in the exhaust air exceeds the pre-heat and pre-cooling needed to maintain supply air conditions. During these periods of time, controls typically reduce the energy recovery capacity to match the reduced load. If the energy recovered in the exhaust is not needed then it is rejected from the facility. By using a water-to-water recovery system, it is possible to significantly reduce overall building energy use by reusing heating or cooling energy generated in the building before it is rejected to the outdoors. Laboratory managers are encouraged to perform a life-cycle cost analysis of an energy-recovery technology to determine the feasibility of its application in their laboratory. Usually, the shortest payback periods occur when the heating and cooling load reduction provided by an energy recovery system allows the laboratory to install and use smaller heating (e.g., hot water or steam) and cooling (e.g., chilled water) systems that eliminate energy waste.