criteria for specified air changes per hour, would restrict the conversion
of these spaces for S/KI TB patient treatment.
3.22.5.1.3 RADIANT CEILING PANELS: The areas equipped
with radiant ceiling
panels in the cooling mode can be retrofitted as S/KI
TB isolation rooms
and TB treatment rooms. However, the modifications to
the existing HVAC
system would be costly and technically difficult. See
explanation below:
(a) The conditioned minimum ventilation air supplied to the spaces will
not be sufficient to meet the air changes per hour requirement. The
necessary modifications to the air-handling unit and air distribution
ductwork would be costly.
(b) The room temperature control sequence will require extensive changes
and the technical feasibility is questionable. Typically, a room
thermostat controls the space cooling requirements by modulating an
automatic flow control valve installed in the chilled water piping serving
the radiant ceiling panels. The minimum room ventilation air is cooled and
dehumidified to remove the space latent heat gain (in addition to the
space sensible heat gain) is uncontrolled at room level. If the
ventilation air volume is increased up to the specified air changes per
hour, in most instances, it will be able to meet the total cooling needs
of the space without any assistance from the radiant ceiling panels.
Consequently, to avoid conflict with the radiant ceiling panels, the
conditioned ventilation air cannot remain uncontrolled and a suitable room
temperature control sequence must be devised so that both cooling sources,
radiant panels and ventilation air, are under the control of one room
thermostat. Such a sequence will invariably involve reheating of
ventilation air resulting in the loss of energy. Besides, should there be
any increase in the level of occupancy (e.g. waiting areas, treatment
rooms etc.), there is a distinct possibility of condensation of moisture
on the panel surface.
3.22.5.2 NEW CONSTRUCTION: For new construction, "all air" systems shall
be provided. The system may be dedicated for tuberculosis care if the
layout of the areas is such that all related functions can be grouped
together on one ward, as it might be in areas of high incidence of the TB.
However, often the S/KI TB isolation rooms and TB treatment areas are
distributed in the facility. In this case, the areas can be served by the
"all air" systems serving the adjoining spaces. In addition to the
requirements outlined in Paragraph 3.22.5.1 for all air systems, the
dedicated systems shall have the following additional features:
(1) 100 percent outdoors air for the dedicated air-handling unit.
(2) Single zone, constant volume reheat (CVRH) system.
(3) Double wall construction.
(4) Horizontal or vertical, draw-thru configuration. Blow-thru
configuration shall not be used.
(5) The unit shall be equipped with 30 percent ASHRAE test efficiency pre-
filters and 90 percent ASHRAE test efficiency after-filters. Utilize HEPA
filters for areas, where required above, in lieu of 90 percent after-
filters.
HVAC DESIGN MANUAL
3-30
HVAC REQUIREMENTS FOR OCCUPIED AREAS
Previous Page
