Basic Documentation

Laboratory Ventilation Codes and Standards
Siemens Industry, Inc. 118
Topic Requirement(s) Commentary
Energy
Conservation
(Continued)
ASHRAE, 2011 Handbook - HVAC Applications, Laboratories, Pg. 16.18 – 16.19
ENERGY
Efforts to reduce energy use must not compromise standards established by safety
officers.
Energy reduction systems must maintain required environmental conditions during
both occupied and unoccupied modes.
Energy can be used more efficiently in laboratories by reducing exhaust air
requirements. One way to achieve this is to use variable volume control of exhaust air
through the fume hoods to reduce exhaust airflow when the fume hood sash is not fully
open. Any airflow control must be integrated with the laboratory control system,
described in the section on Control, and must not jeopardize the safety and function of
the laboratory.
Setback controls that reduce ventilation rates when the laboratory is unoccupied can
also reduce energy consumption. Timing devices, sensors, manual override, or a
combination of these can be used to set back the controls at night. If this strategy is a
possibility, the safety and function of the laboratory must be considered, and
appropriate safety officers should be consulted.
Fume hood selection also impacts exhaust airflow requirements and energy
consumption. Modern fume hood designs use several techniques to reduce airflow
requirements, including reduced face opening sashes and specifically designed
components that allow operation with reduced inflow velocities.
Energy can often be recovered economically from the exhaust airstream in laboratory
buildings with large quantities of exhaust air. Many energy recovery systems are
available, including rotary air to-air energy exchangers or heat wheels, coil energy
recovery loops(runaround cycle), twin tower enthalpy recovery loops, heat pipe heat
exchangers, fixed-plate heat exchangers, thermo siphon heat exchangers, and direct
evaporative cooling. Some of these technologies can be combined with indirect
evaporative cooling for further energy recovery.
Concerns about the use of energy recovery devices in laboratory HVAC systems
include (1) the potential for cross-contamination of chemical and biological materials
from exhaust air to the intake airstream, and (2) the potential for corrosion and fouling
of devices located in the exhaust airstream. NFPA Standard 45 specifically prohibits
the use of latent heat recovery devices in fume hood exhaust systems.
Energy recovery is also possible for hydronic systems associated with HVAC. Rejected
heat from centrifugal chillers can be used to produce low-temperature reheat water.
Potential also exists in plumbing systems, where waste heat from washing operations
can be recovered to heat makeup water.
Energy recovery systems for laboratory
applications require considerable more
careful examination than such systems for
non-laboratory applications mainly due to the
potential for cross-contamination and
corrosion.