A surprising way to save energy on your existing infrastructure
Energy consumption is a big topic in building operations, especially in light of today’s challenges around the climate crisis and ever-rising energy costs. It is thus not surprising that building operators are on the lookout for ways to increase the energy efficiency of their buildings.
In this context, the Heating, Ventilation and Air Conditioning (HVAC) system installed in the building is often the first target, as it is usually the biggest energy consumer. Unfortunately, it is usually challenging to retrofit energy efficiency measures into existing buildings as most available solutions focus on the production of cooling, i.e. replace existing chillers and compressors with more energy-efficient ones or install Variable Speed Drives (VSD) for pumps. These expensive measures tend to yield very long-term ROIs and can come with a lot of installation effort and disruption to ongoing operations.
There is however another often overlooked angle for energy optimization: optimizing the consumption of cooling. Currently, most hotels stop at installing a keycard energy switch in their guest rooms, but there is much more that can be done. Waste cooling consumption in rooms can come from many factors such as:
- Over cooling by setting the HVAC to very low setpoints
- Inefficient room allocation
- Lack of maintenance of the Fan Coil Unit (FCU)
- Cooling empty/unoccupied rooms
So what can you do about these?
How to reduce overcooling?
Here at SensorFlow, we have recorded the usage data of hundreds of thermostats in Southeast Asia which allowed us to develop a deep understanding of how people use them and what are the most common AC settings chosen by guests. One thing that we found over and over again in our data is the evidence that the vast majority of people are comfortable at a temperature level between 22 – 25°C.
Unfortunately, most thermostats on the market allow users to choose a setpoint well below this range, often down to 16°C. The ability for guests to choose setpoints way below their comfort level leads to a lot of energy wastage as it promotes the wasteful usage pattern we see over and over again in our data.
Guests will choose the lowest available setpoint when they first enter an uncooled room with the expectation that a lower setpoint will lead to the room cooling faster. This is based on the misconception that the setpoint defines the temperature of the air coming out of the fan coil and not the target room temperature. Due to this, the AC will cool the room far below what is experienced as comfortable by the guest and thus we quickly see the guests raising the temperature back to something between 22 – 25°C. To prevent this energy waste resulting from overcooling, a good policy is to limit the lowest selected setpoint to something that is closer to the average user’s comfort zone. The SensorFlow HVAC automation system allows you to do this with the click of a button and we consult our clients as to what setpoint limitation level they should ideally choose based on the data we record. We have implemented setpoint limitations at 23°C in properties without causing guest complaints, reducing HVAC consumption in the room by up to 10% with this action alone. As a matter of fact, this often increases guest comfort as it removes the overcooling of the room which will result in guests feeling cold. Should a guest still feel that the room is not getting cold enough, the setpoint limitation can be reduced or removed equally fast through our dashboard, without the need of an engineer entering the guest room.
Inefficient room allocation
Many hotels are currently operating under low or very low occupancy due to the pandemic resulting in travel restrictions. In this scenario, one thing that often gets overlooked is the impact of low occupancy on the overall building’s efficiency and many are surprised to find out how much of an impact guest room allocation can have on your hotel’s overall energy consumption.
Most HVAC systems are designed to be most efficient under full or almost full load, i.e. the more rooms are being cooled the less energy is used per individual room. This works great during high occupancy but quickly becomes a problem when hotels have to cool only a single room when a whole VRV bank is designed to service 15 rooms. In these scenarios, the energy required to cool one room can easily triple, eating away the little profits the hotel was hoping to make from renting out even a small amount of rooms. In a big property, it can make a huge difference if you are running 15 VRV banks to cool 15 rooms or just one.
There are many other factors that can impact energy consumption when it comes to room allocation:
- Sun-facing or corner rooms will consume more energy than other rooms as they are more exposed to external heat
- Unrented rooms between rented-out rooms will increase energy consumption in their neighbouring rooms as they will require passive cooling through the walls.
- Rooms with poorly maintained fan coils will use more energy than rooms with recently serviced fan coils.
But how would you know which room to allocate a reservation to if there are so many factors to consider? A basic rule to follow that can help to improve the situation is to allocate north-facing rooms first and try to allocate all booked rooms next to each other on the same floor or on floors above and below.
At SensorFlow, we go one step further. With our patented SmartALLOC technology, we use our real-time detailed data of your HVAC system’s performance to automatically calculate the next best, most energy-efficient room to allocate to a given reservation. The SensorFlow system develops a deep understanding of your HVAC system and calculates an efficiency score for every room in your property with respect to the present occupancy and all the aforementioned factors. This enables your front-of-house staff to play an important role in your energy savings initiative, by empowering them to always allocate the most energy-efficient room to a reservation. Through further integration of this solution with your PMS system, we can turn this into an effortless step during your check-in process. Our studies have shown that this can save up to 30% of overall HVAC usage during low occupancy.
Cooling of empty rooms
It is generally good practice in hotels to have some form of key card system installed, it’s supposed to switch off energy whenever the guest is not in the room. These key card systems however often have significant drawbacks:
- Guests can override them with extra key cards, name cards, or credit cards
- Key cards, in general, are getting out of fashion with regards to contactless and self-check-in processes
- Key cards are all or nothing, either switching the whole unit on or off and not individual rooms.
To address the common issues faced by keycard systems, modern solutions are focusing on the use of occupancy detection systems rather than key cards. While this helps with preventing keycard bypass and enables energy savings, even if a contactless check-in process is used in combination with smart locks, it does enable another often unrecognized opportunity for energy savings in suite rooms. If the installation of occupancy sensors is combined with the use of smart thermostats such as the ones installed as part of the SensorFlow system, more energy savings can be generated in spaces with multiple rooms. Take for example a suite with a living room and a bedroom. In this setup, the HVAC system can be configured to automatically switch off in the living room at night once it’s detected as empty once the guests go to sleep in the bedroom. Key card systems are not able to perform this fine-grained level of automation which can save 5-8 hrs of cooling/heating in suite-style rooms per night, leading to a significant reduction in energy consumption.
A big concern regarding the measures described in this article is often the maintenance of guest comfort in the rooms. Many people shy away from implementing measures on the consumption side in fear of creating additional guest complaints. This is a valid concern, especially with regards to thermal comfort, which is one of the most difficult parameters to optimize as preferences vary widely between people. There can never be a one size fits all solution. This makes it important to constantly monitor the impact of optimizations on the consumption side regarding guests complaints and HVAC performance and thus demands a system that is easily configurable and can be adapted to changing situations and demands.
SensorFlow’s solution offers remote and real-time configuration so that each optimization can be tuned to the guest’s preference without entering the guest room. This empowers employees to efficiently address guest complaints and prevents unwanted intrusions into the guest’s space, ultimately leading to higher guest satisfaction and lower energy consumption.
If you want to know how SensorFlow’s solution can help your hotel be more energy-efficient, contact us here!