DG 1110-3-146
Design Guide: Military Police Facilities
December 1979
General Planning and Design Guidance: Environmental Services
conditioning (HVAC); plumbing; and electrical. The
ponent of a sub-system consider the long-term implica-
tions for obsolescence as they affect performance and
following descriptions of each sub-system are intended
cost. For example, a roof-top air conditioning unit has
to familiarize the non-technical user with various criteria
involved in sub-system selection and design, and to pro-
relatively low initial cost compared with other systems,
but an expected useful life of only 15 years, after which
vide guidance to the engineer and architect.
time it will probably require extensive repair or replace-
ment. Thus, over the life of the building, the compara-
system for a building is generally concerned with pro-
tively shorter useful life of a sub-system might offset
viding a comfortable interior climate. While the technical
the initial cost advantage.
meaning of the word "air conditioning" includes heating
and ventilating, it is commonly used as a synonym for
c. LIFE CYCLE COST In addition to obsolescence,
cooling. It is used both ways here, depending on the
the total life cycle or operating cost of the major com-
context. For standard applications, refer to DOD Con-
ponents of environmental services sub-systems must
struction Criteria Manual 4270.1-M and to Technical
be considered. This total cost comprises the initial in-
Manual TM 5-810-5.
stalled cost, the maintenance cost and the energy cost
of the component over its useful life. For example, if
(1) Weather Zones Refer to DOD Manual 4270.1-M
it is known that the initial installed cost of large refrigera-
for definitions of weather zones, inside temperature
tion equipment using air-cooled condensers is less than
and humidity to be maintained, and, under Program-
the initial installed cost of refrigeration equipment using
ming Priorities, whether or not military police build-
water-cooled condensers, but the energy cost of equip-
ings are to be provided with comfort cooling systems.
ment using air-cooled condensers is substantially
The number of hours of wet bulb and dry bulb for
higher; then the total owning and operating costs (the
the site will be obtained from Technical Manual TM
life cycle cost) would generally be higher for air-cooled
5-785, "Engineering Weather Data."
refrigeration equipment. Invariably, large refrigeration
(2) Comfort Conditions In order to get comfortable
equipment will employ water-cooled condensers unless
temperature conditions close to windows, and in
other factors govern the selection of major sub-system
order to maintain comfortable humidity levels inside
components, such as a lack of makeup water, etc.
the building, consider the use of double glass or
storm sash in buildings located in cold weather
d. EXPANSION In designing environmental services
zones. Wherever a building is to be air conditioned
sub-systems, consider the need for future expansion
(cooled), consider tinted glass, double glazing, and/
of each sub-system due to expansion of the building.
or storm windows, thus reducing the size, initial cost
Solutions may involve providing spare capacity when
and operating cost of the air conditioning system.
expansion of the building in the near future is prob-
As a protection against over-dependency on artificial
able. Also, the provision of space for additional equip-
systems in critical operational areas, well-sealed,
ment for possible extension of the building in the longer-
operable windows should be provided, especially in
term future should be considered. Nothing in thedesign
all exterior spaces under 160 square feet.
of any environmental services sub-system should pre-
clude the replacement or relocation of equipment when
c. HEATING The heating is usually provided by hot
extension of the building has been definitely projected.
water obtained from a central heating plant on the in-
Such provisions for future expansion always result in
stallation or from a boiler in the building. If the installation
an increase in costs. The need for and timing of ex-
has either a central steam or high temperature water
pansion should be carefully evaluated before a decision
system, heat exchangers should be provided in the
is made to program for it in order to justify the addi-
building to heat water that can then be pumped to the
tional costs involved. Another possibility is to provide
various areas of the building.
for incremental growth by requiring any future expan-
sion to be accomplished by constructing fully serviced
modules with their own environmental systems. In this
(1) Cabinet Heaters Fan-type unit heaters should
particular case, although the initial building construction
be provided at all entrances and in all lobbies, stairs
programs may be left unaffected, the site utilities re-
with exterior walls, mechanical equipment rooms
quirements must include or permit provisions for
and other such areas requiring heat. Cabinet heaters
modular expansion of environmental services.
will not be provided where outdoor design tempera-
ture is +20 degrees F or higher. Whenever a large
group of people enters or leaves a building, both
3-8
the inner and outer doors of the vestibule are open
Environmental Service
and large amounts of cold air enter the lobby. Thus,
wherever a lobby has a vestibule, a cabinet-type
Sub-Systems
unit heater in the lobby is to be preferred to one in
the vestibule for quick recovery and more stable
a. GENERAL Environmental services are divided into
lobby conditions.
three major sub-systems: heating, ventilating and air-
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