Simulations of Indoor Air Quality and Ventilation Impacts of Demand Controlled Ventilation in Commercial and Institutional Buildings.
Simulations of Indoor Air Quality and Ventilation
Impacts of Demand Controlled Ventilation in Commercial
and Institutional Buildings.
(2081 K)
Persily, A. K.; Musser, A.; Emmerich, S. J.; Taylor, A.
W.
NISTIR 7042; 50 p. August 2003.
Sponsor:
Architectural Energy Corp., Boulder, CO
Available from:
Orders Only) 800-553-6847;
Website: http://www.ntis.gov
Keywords:
ventilation; commerical buildings; institutional
buildings; carbon dioxide; energy efficiency; indoor air
quality; volatile organic compounds; simulation
Abstract:
Carbon-dioxide (CO2) based demand controlled ventilation
(DCV) offers the potential for more energy efficient
building ventilation compared with constant ventilation
rates based on design occupancy levels. A number of
questions related to CO2-based DCV exist regarding
potential energy efficiency benefits, optimal control
strategies for different building types, and sensor
performance and deployment. In addition, questions have
been raised concerning the indoor air quality impacts,
primarily with respect to contaminants with source
strengths that are not dependent on the number of
occupants. In order to obtain some insight into the
issue of IAQ impacts of CO2-based DCV, a simulation
study was performed in six commercial and institutional
building spaces using the multizone airflow and IAQ
model CONTAMW. These simulations compared six different
ventilation strategies, with four of them using CO2 DCV,
the simulations, performed for six U.S. cities, were
used to compare ventilation rates, indoor CO2 levels,
indoor concentrations of a generic volatile organic
compound (VOC) as an indicator of non-occupant
contaminant sources, and energy impacts. The results
indicate that these impacts are dependent on the details
of the spaces including occupancy patterns, ventilation
rate requirements in the relevant standards and
ventilation system operating schedule as well as the
numerous assumptions used in the analysis, including
contaminant source strengths and system-off infiltration
rates. For the cases studied, the application of CO2 DCV
resulted in significant decreases in ventilation rates
and energy loads accompanied by increased indoor CO2 and
VOC concentrations. The increases in CO2 were not
particularly large, in the range of 180 mg/m3 (100 ppm
(v)). The indoor VOC levels increased by a factor of two
or three, but the absolute concentrations were still
relatively low based on the assumed emission rates. The
annual energy load reductions due to the use of CO2
control were significant in most of the cases, ranging
from 10% to 80% depending on the space type, climate and
ventilation strategy.
