Basic Documentation

Siemens Industry, Inc. Page 7 of 12
Document No. 149-822
The following mandatory controls are required for
HVAC sy
stem energy efficiency:
 Zone isolation (6.4.3.2.4)
 Shutoff Damper Control (6.4.3.3.3)
 Low-leakage Dampers (6.4.3.3.4)
 Ventilation Fan Shutoff (6.4.3.3.5)
 Humidifier Preheat (6.4.3.5)
 Freeze Protection (6.4.3.7)
 Demand Control Ventilation (6.4.3.8)
Duct Leakage–Mandatory Provisions
HVAC systems are large, custom, sheet metal
structures built under tight cost constraints.
Typically, they leak. Leakage wastes energy. When
the supply ducts leak, conditioned air gets lost on its
way to the rooms. It adds to the total energy load,
without accomplishing a result. When exhaust ducts
leak, air is drawn from interstitial spaces or other
areas without improving air quality in the zones.
ASHRAE 90.1-2004 documents mandatory HVAC
system duct leakage provisions in section 6.4.4.2 of
the standard. Duct leakage tests should be written
into the contract documents to communicate to the
mechanical contractors so they can select the
appropriate materials and construction processes.
It is important that air stream surfaces comply with
section 6.2 of ASHRAE/ASHE/ANSI Standard 170-
2008, Ventilation of Health Care Facilities to resist
mold growth on air stream surfaces.
Factory-fabrication of terminal units provides a
turnkey solution that provides terminal unit, controls
and hydronics preassembled and leak-tested in a
complete package. These ultra-low terminals pass
less than 1 cfm at a static pressure of 1 in. WC,
compared to 3 cfm leakage from terminals with
standard construction. Sealed terminal units are
available from manufacturer upon on request. All
box seams and joints are sealed with an
environmental friendly water based adhesive. This
sealing essentially eliminates all box air leakage to
the plenum air space. This means all conditioned
primary air makes it to the zone being controlled,
and will not leak to the return air plenum. The
incremental cost of tighter terminal pays for itself in
three to five years, early in the useful life of the
building.
Controls–Prescriptive Provisions
ASHRAE 90.1-2004 documents prescriptive
automatic control provisions in section 6.5 of the
standard.
Eliminate Simultaneous Heating and
Cooling
Elimination of simultaneous heating and cooling
(section 6.5.2) requires controls that serve zones,
hydronic systems and dehumidification process to
be sequenced to prevent reheating, recooling or
mixing of mechanically cooled or heated fluids or air.
Reduce Ventilation Fan Energy and Cooling
In healthcare facilities, ventilation systems are
designed to:
 Maintain the indoor environment at comfortable
levels for healthcare workers, patients and
visitors.
 Control odors.
 Remove contaminated air.
 Minimize risk of transmission of airborne
pathogens.
The primary way in which the ventilation system
assists in the infection control process is through
Ventilation (for example, dilution of contaminants),
Pressurization (for example, containment of
contaminants), and Filtration (removal of airborne
infectious agents).
Reducing energy usage can be conserved by
reducing ventilation air during unoccupied periods
and moving the air more efficiently. The FGI 2006
guidelines include the provision for reducing the
number of air changes when the room is
unoccupied, provided that the room pressurization is
maintained.
12
Reducing the number of air changes per hour during
unoccupied hours in operating rooms has significant
impact on energy costs. A recent hospital design
review study found that five of the ten operating
rooms examined, could have reduced supply air
flows by 20% to 56% of the occupied flows to
conserve energy while still maintaining the desired
room pressurization.
13
FGI 2006 guidelines do not
specify an unoccupied air change rate, but does
require pressurization to be maintained at all times.
12. Guidelines for Design and Construction of Hospital and
Health Care Facilities, 2006. Washington, DC, The Facility
Guidelines Institute., p. 121, section 10.2.2.4(3)(b)
13.
Richard Hermans, Martha Hewett, Chad Colsh; Strategies
to Reduce the Spread of Airborne Infections in Hospitals:
Review of Hospital Designs, National Institute of Standards
and Technology, NIST GCR 06-887, October 2006, p. 10