San Francisco's Orchard Garden Hotel was San Francisco's first
hotel to implement a cardkey system to control lights and HVAC
systems in guestrooms. Monitored data from four rooms in the hotel
showed a reduction in heating and cooling energy of 45% during the
peak cooling season (See Figure 1). Computer simulations based on
monitored occupancy levels in the hotel estimate a savings of 32%
of annual heating and cooling costs. Modeled across five different
climate zones, the average savings were 26%.
Figure 1. Energy use for one month in
four rooms with and without guestroom controls
Figure 2. A cardkey receptacle
The cardkey system is explained to guests when they check into
the hotel. After a guest enters a room using their cardkey,
they place the card in a special receptacle near the
entrance. Inserting the card into the receptacle signals the
guestroom controls to turn the system components onto occupied
mode. That signal will bring the thermostat setting back to
the desired temperature during occupancy and permit lights,
televisions, and other equipment to turn on.
When exiting the room, the guest takes the key with them,
automatically "turning off" the entire room once the key is removed
from the receptacle. Had the occupant failed to turn off the
television, for instance, it would then be shut down. At least one
outlet is excluded from the system so that guests can charge
laptops, cell phones, and other battery-powered devices while they
are out of the room.
Guest feedback of the system at the Orchard Garden Hotel has
been mostly positive. Stefan Muhle, general manager, believes
that "while most international guests find it commonplace, those
who are new to the technology have become quite fond of it."
Mr. Muhle says that instructions given upon check-in make the
guests comfortable using the system and "make the guests feel
positive about saving energy."
The hotel industry is fertile ground for saving energy.
Guestroom energy uses account for 40%-80% of total hotel energy
costs, and those rooms are unoccupied much of the time. Nationwide
estimates for guestroom energy expenses suggest that 80% is for
heating and cooling, the remaining 20% is for plug loads and
lighting. (1)
Typical hotel HVAC systems are designed to maintain a guestroom
at a fixed temperature both day and night. In many hotels - whether
the guests are business or leisure travelers - the rooms are
frequently unoccupied for much of the day. During those
times, it will save hotels money to setback the thermostat or
completely turn off the heating and cooling. Guestroom
control systems accomplish just that.
Further, a significant portion of hotel rooms remain "unrented"
at any given time. PKF consulting reports an average 77%
rental rate for hotels in Northern California and the Central
Valley. For hotels that leave HVAC systems in guestrooms running
all the time, this vacancy rate offers another significant
opportunity to save energy with guestroom control systems.
Guestroom control systems can be installed in new and existing
hotels, with the biggest opportunity for energy savings in the
substantial stock of existing hotels. Hard-wired systems will
be cost-effective only for new construction or major
renovations. Wireless systems are available that are well
suited for retrofit installations in existing hotels.
Guestroom control systems can be configured to:
- Manage either fan coil units or self-contained through-the-wall
air conditioning units (PTAC units).
- Draw the curtains once a guest leaves the room to reduce solar
gains through the window. This can significantly increase
savings.
- Setback the thermostat when a window or patio door has been
left open.
The primary benefit of guestroom control systems is that they
reduce energy use for the hotel. By either setting back the
thermostat or shutting the HVAC unit off when the room is
unoccupied, they reduce cooling and heating energy use. Some
systems can also control lighting and receptacle loads. Not
all lights and outlets are controlled, since some need to remain on
to power clocks, telephones, and devices plugged in by guests.
A second benefit is that occupancy controls reduce peak
demand. Hotel rooms are frequently unoccupied during
afternoon hours when electricity demand is highest. By
reducing peak loads, there is an opportunity to downsize central
cooling systems for new installations in large hotels or during
system replacements. Utility demand charges are also
reduced.
Figure 3. Monitored Guestroom
Occupancy. Monitored occupancy data from two hotels shows
that occupancy is very low during the afternoon hours when
electricity demand is typically highest
Cost Effectiveness
Some guestroom control systems can be integrated with energy
management systems, which offer centralized control of room
comfort. One advantage of centralized control is that the
system can apply a wider temperature setback when a room is
unrented since it does not need to be ready to return to a target
occupancy temperature on as short of notice. The wider
temperature setback in turn results in greater energy
savings. The centralized control also permits the
implementation of building-wide demand management strategies when
desired.
Some products offer additional features such as displaying
occupancy status to housekeeping staff so that they do not disturb
a guest. While such features do not have direct energy benefits,
they may lead to a more pleasant stay for guests. Drapes that
close automatically when a room is unoccupied will also minimize
fading of upholstery and decorations, adding to their useful life.
A system recently introduced into the marketplace provides control
of room temperature, lighting, and a "do not disturb" sign through
the television remote.
One concern with the cardkey system is that guests may insert a
second or spare key into the slot when leaving the room to minimize
their inconvenience, thus defeating the controls. Cardkey
systems are more prevalent in Europe and Asia and guests there have
a positive perception of the controls. A recent guest survey
for a hotel with the cardkey system showed that the vast majority
of the guests felt positively about the system and did not consider
it to be an inconvenience. While many noticed a change in
room temperature upon returning to the room, most found it to be
acceptable.
The occupancy sensor systems have an advantage over the cardkey
systems in that they do not require guest interaction. However,
there is a concern that guests unfamiliar with the occupancy
sensors may mistake them for cameras or other monitoring devices
that compromise their privacy. Some occupancy sensors are
integrated into the thermostat to minimize this perception. Other
occupancy sensors are available that are designed to look like
smoke detectors to minimize guest concerns.
1. "Technology: Energy management systems save
hoteliers money" Whitford, M., Hotel & Motel Management Dec
1998.
2. "Card-Key Based Guestroom Controls Evaluation
Report", PG&E, 2007 and "Occupancy Based Guestroom Controls Evaluation
Report", PG&E, 2007. The report cites previous
studies by ACEEE, Lau and Muhle in estimating savings and payback
period.
| Training Highlights |
|
California utilities offer outstanding educational opportunities
that focus on the design, construction and operation of energy
efficient buildings. Listed here are a few of the many upcoming
classes and events; for complete schedules, visit each utility's
website.
Efficient Air Conditioning and Energy Management
Systems
This course will cover specific efficiency features of
small-tomedium- size air conditioning systems, shed some light on
the SEER and EER rating methods, and explore air conditioning unit
replacement economics. Offered in San Diego on January 14,
2010.
read more...
Technology Update
Facility staff and management professionals will learn about
current energy efficient technologies used in commercial and
industrial businesses. Topics include lighting, chilled water
systems, electric motors, drives, energy management systems, HVAC,
and distributed energy resources. Attendees will learn how to save
money by implementing basic technology changes. Offered in Tulare
on February 4, 2010 and in Irwindale on January 12 and 13,
2010.
read more...
|
Basic Programmable Logic Controllers: Energy Efficiency
Applications
Management, operations, and maintenance professionals will learn
the basics of how Programmable Logic Controllers (PLCs) operate in
an industrial process and how they can be used for energy efficient
applications. Participants will develop a basic understanding of
Programmable Logic Controllers terminology, how the hardware
components are used, and the basics of relay ladder logic. Offered
in Irwindale on March 16, 2010.
read more...
Energy Management Systems
This one-day seminar presents a review of common HVAC system
configurations, the fundamentals of how energy management systems
(EMS) are constructed and how they work, an overview of
communication networks, and how EMS are able to maximize energy-use
savings. It focuses on how to maximize savings using the most
current technology in HVAC control methods. In addition, the
seminar presents a practical, systematic approach for identifying,
designing, and planning the implementation of an energy management
control system. This seminar is recommended for those who have some
understanding of HVAC systems and desire to know more about saving
on operating costs with an EMS. Offered in San Diego on February 9,
2010.
read more...
|
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