Ventilation Strategies for U.S. Manufactured Homes.
Ventilation Strategies for U.S. Manufactured Homes.
(664 K)
Persily, A. K.
Health Buildings 2000, 6th International Conference.
Proceedings. Volume 2. Design and Operation of HVAC
Systems. August 6-10, 2000, Espoo, Finland, 291-296 pp,
2000.
Keywords:
ventilation; predictive models; manufactured housing;
air change rate; infiltration; modeling; residential
buildings; standards
Abstract:
The HUD Manufactured Home Construction and Safety
Standards contain requirements intended to provide
adequate levels of outdoor air to the occupants of
manufactured homes. In the implementation of these
standards, questions have arisen regarding the impact
and significance of some of these requirements. Some of
these questions relate to the actual ventilation rates
in homes built to the standards and the means of
providing supplemental mechanical ventilation to meet
the standard's requirements. Other questions concern how
specific ventilation system components such as duct
leakage, local exhaust fans and air inlets affect
ventilation rates, air movement patterns, and building
pressures. In order to obtain some insight into these
issues, the multizone airflow and indoor air quality
simulation program CONTAM was used to simulate a
double-wide unit under several different ventilation
scenarios. These scenarios include envelope infiltration
only, infiltration plus the effects of local exhaust and
forced-fan operation, an outdoor air intake duct
installed on the forced-air return, and whole house
exhaust with and without passive inlet vents.
Simulations were performed to predict outdoor air
ventilation rates into the house due to infiltration and
mechanical ventilation, air flow rates between the
rooms, building pressures, and ventilation air
distribution. Annual simulations were performed in three
cities to assess ventilation rates and energy
consumption associated with these scenarios. The results
show that despite the assumption in the HUD standards
that infiltration contributes 0.25 h-1, the predicted
infiltration rates are lower than this value for many
hours of the year. The supplemental ventilation systems
investigated in this study provide ventilation rates
that meet or exceed the total ventilation requirement of
0.35 h-1, but the impacts of such systems are dependent
on their operating schedules. The results of these
simulations are presented and discussed, and
recommendations are made for changes to the HUD
standards and the ventilation of manufactured homes.
Building and Fire Research Laboratory
National Institute of Standards and Technology
Gaithersburg, MD 20899