Heating, ventilating and air conditioning (HVAC)
account for some of your highest energy expenses, but these
systems are also critical to your guests' comfort and satisfaction.
If your facility is too cold or too hot, you can expect
complaints. HVAC systems
also contribute to your facility's air quality, and fresh
air is particularly important in enclosed or high-odour
areas. For optimum efficiency, ensure that the functions
of each HVAC component
complement the others - especially when ventilation systems
help distribute warm and cold air.
There are many types of HVAC systems,
but the majority of hotels and restaurants in Canada use
self-contained, packaged systems that combine heating, ventilating
and air conditioning. Rooftop HVAC units
(RTUs) are often used in single-zone, single-storey
buildings, such as restaurants. Incremental
or packaged terminal air conditioners
(PTACs) enable discrete control in each suite and
are commonly mounted to outside-facing walls or below windows
in guest rooms of small to mid-size hotels and motels. Fan coil units are a component of central systems
used in mid-sized and larger hotel facilities. In these
systems, air is blown over coils that have been heated by
boilers or cooled by chillers
in a central plant. Savings can also be realized
with the efficient use of cooling towers, air-to-air
heat exchangers, air-handling units (AHUs), heat pumps and other HVAC components.
Common HVAC Measures
Pick the right system when
replacing your HVAC
unit, usually at the end of its life cycle. In addition
to energy efficiency, the size, weight, maintenance
costs and noise levels are important considerations.
Outdoor air economizers should
be included with air-handling units, so outdoor air
can be used for free cooling during spring
and fall or on cool summer nights when the humidity
level is not too high.
Smart thermostats provide
preset limits for heating and cooling - overriding unnecessarily
high or low settings by guests or staff. These thermostats
also feature digital controls and readouts that ensure
greater accuracy than the sliding levers on traditional
Night temperature setbacks involve
the installation of an automatic thermostat that controls
the temperature when a restaurant, for example, is closed.
Heat recovery ventilators (HRVs)
and energy recovery ventilators
(ERVs) have balanced exhaust and supply fans
that meet all ventilation needs without creating drafts
and air-pressure imbalances. HRVs can feature efficiencies
as high as 85 to 95 percent, with payback in roughly
3.5 years. Consider these units whenever air is continuously
exhausted and make-up or ventilation air is required.
Variable-speed drives (VSDs),
described in the Motors and Drives section,
can be used with variable-air-volume
(VAV) systems to adjust fan speeds according
to operating requirements at different times of the
day. In kitchens, for example, fans can be linked to
burners to reduce energy consumption during off-peak
cooking periods. Be careful, however, not to cut exhaust
to the point that kitchen odours permeate other areas
of your facility.
Zone isolation and demand control ventilation (DCV) reduce airflow
when low carbon-dioxide levels indicate a room is not
in use. Implementing these measures may involve the
use of variable-frequency drives (see the Motors
and Drives section) and shut-off dampers, as well
as reductions in the amount of outside air used by your
system. Energy is saved not only because air distribution
is reduced, but also because less air must be heated
Removable and re-usable insulation
for pipes, valves and fittings is made of non-combustible
materials and can provide paybacks as short as four
months. Traditional insulation is often not replaced
once it has been removed or damaged during maintenance.
This can lead to tremendous heat loss or gain, as well
as condensation and safety hazards. Removable and re-usable
insulation provides a solution by simplifying both maintenance
access and thermal-barrier replacement.
Proper maintenance is critical
to any system, since it helps reduce operating costs,
extends operating life and avoids costly repairs. This
is especially true with cooling towers, which are subject
to scale deposits, clogged nozzles, biological growth,
poor airflow and poor pump performance. These factors
can diminish performance and raise operating costs by
10 to 25 percent. For air-handling units, buying high-quality
filters will reduce air-borne dust and contaminants.
In new boilers, proper maintenance can deliver savings
of up to 20 percent. Look for more maintenance information
in the Energy Tips section of this guide.
High-efficiency condensing boilers
will save you a great deal of energy when it
is time to replace old boilers. These units can achieve
seasonal efficiencies as high as 96 percent (compared
with 75 percent for old boilers). Incremental paybacks
of two to six years are common compared with purchasing
midrange replacement boilers, but initial costs can
be twice as high. For example, the piping distribution
and terminal-heating units may need to be redesigned
for condensing boilers.
Boiler flue gas economizers are
heat exchangers that preheat water using boiler-stack
and exhaust gases. With installed costs of approximately
$35,000, economizers deliver a 5 to 10 percent increase
in efficiency and, in large facilities, paybacks of
four to 10 years.
Air preheaters use hot stack
gas to preheat fuel and air prior to combustion. These
units cost approximately $15,000 and have paybacks in
2.5 to 3.5 years.
Boiler combustion and oxygen-trim systems minimize energy loss by
reducing the amount of excess air or fuel in a boiler
stack. An automated oxygen-trim control system ensures
the proper fuel-to-air mixture is maintained. With a
typical cost of $10,000 for a 300-horsepower boiler,
these units deliver energy reductions of 1 to 5 percent
and paybacks of approximately five years.
Boiler blowdown heat recovery uses
a heat exchanger to extract thermal energy from hot
water that is continuously drained from a boiler. Prices
range from $10,000 to $35,000, depending on the amount
of steam supplied. Paybacks are approximately 6.5 years.
Continuous boiler blowdown monitoring
and control systems reduce the amount of hot
water continuously drained from boilers. These systems
typically cost $2,500 to $6,000, with approximate paybacks
of five years.
Automatic vent dampers for boilers
prevent residual heat from being drawn up the
warm stacks, reduce the amount of air that passes through
furnaces or boiler-heat exchangers and improve comfort
conditions during the winter by helping retain humidity
in a building.
Energy-efficient chillers have
better controls, condensers and compressors than regular
units. Their costs, however, may not always yield reasonable
paybacks and may not make up for inefficiencies in other
parts of air-conditioning systems, such as pumps, cooling
towers and controls.
Refrigerants themselves can
save you energy. For example, chillers that use an HCFC-123
refrigerant currently have the highest energy efficiencies,
at 0.49 kW per ton.
Thermal energy storage (TES)
enables you to store cool water for later use as an
air coolant. This function is particularly valuable
for use at peak demand times during summer days. Approximate
payback is 10 years.
The Vocabulary of HVAC
Btu/h, or British thermal units per hour, measure heat
produced by boilers and cold produced by chillers. A single
unit is the equivalent of 0.000295 kW or 0.000001055 GJ/h
(one millionth of a gigajoule per hour).
Boiler hp (horsepower) measures boiler power and is equal
to 33 520 Btu/h, 9.8 kW, 15.7 kg/h of steam or 0.0353636
Boiler efficiency is calculated according to the formula:
output energy divided by input energy multiplied by 100.
Calculations are affected by factors such as thermal efficiency
and fuel-to-steam efficiency.
Chiller efficiency measures power input per ton of cooling
produced by larger chillers. A lower number indicates higher
efficiency. The unit of measurement is kW/ton, in which
ton is the amount of cooling produced when one imperial
ton of ice melts. One ton equals 12 000 Btu/h or 3.516 thermal
Energy efficiency ratio (EER) measures the performance
of smaller chillers and rooftop units (as opposed to the
kW/ton, which is used to measure the power of larger chillers).
EER is calculated by dividing the cooling capacity in Btu/h
by a chiller's power input in watts. The higher the EER,
the more efficient the unit. Standard heat-pump units often
have EER values of 8.9, where higher-efficiency units may
Coefficient of performance (COP) is energy output divided
by energy input. The higher the COP, the more efficient
the chiller or heat pump.
Seasonal energy efficiency ratio (SEER) applies to rooftop
units with cooling capacities less than five tons. SEER
is a seasonally adjusted rating based on representative