The guests have gone home. The bills haven’t.
We talk to a lot of hoteliers in September, and the conversation is usually about the same things. How many room-nights, how the rate held up, whether August was better than last year. What almost never comes up is hotel energy management, even though the electricity bills for June, July and August are sitting in someone’s inbox with a number on them that would make most owners wince.
So here’s the question we’d like you to ask this month, while the season is still fresh: how much of that hotel energy consumption went into rooms that nobody was in?
We think the answer will surprise you. And winter is the only time you’ll have to do anything about it.
Why September is the right time to look at hotel energy management
Energy is the second-biggest cost you can actually control in a hotel. Labour comes first, energy comes second, and according to ENERGY STAR’s commercial building data it’s the one rising fastest. In European hotels it typically eats 3 to 6 percent of revenue. If you run a seasonal property on the coast with a lot of cooling load, you’re at the top of that range, not the bottom.
The trouble is that energy cost is almost invisible while the season is running. Nobody sees the four thousand euros spent cooling empty rooms in July. It turns up weeks later as one line on an invoice, blended in with the kitchen, the pool pumps and the laundry. Nobody’s fault, but nobody’s looking either.
A post-season audit is just a way of pulling that line apart. It’s the starting point for any serious hotel energy management effort, and it costs you an afternoon.
Where the summer’s energy actually went
The pattern for warm-climate hotels is well established:
| What’s using it | Share of summer electricity |
|---|---|
| Cooling and ventilation | 40–50% |
| Hot water | 15–20% |
| Lighting | 10–15% |
| Kitchens, laundry, pools, lifts | 15–25% |
| Everything else | 5–10% |
Two things jump out. Guest rooms are where the money goes; cooling, lighting and minibars in rooms add up to more than half the bill in most resort properties. And the biggest line, cooling, is the one most at the mercy of what guests do.
What guests do is fairly predictable. Occupancy studies in leisure hotels keep finding the same thing: guests are out of their room 60 to 70 percent of the day. On a beach in August it’s probably more. You sell the room for 24 hours, the guest uses it for eight or ten.
Without any room-level control, the air conditioning doesn’t know that. It runs for all 24. That gap, between a room being sold and a room being occupied, is basically the whole story of energy efficiency in hotels.
What that gap costs: a worked example
Let’s put some numbers on a typical Adriatic property. These are assumptions, and you should swap in your own.
Say you have 120 rooms, a season from 1 May to mid-October (call it 165 days), 80 percent average occupancy, and a split or fan-coil unit in each room pulling about 12 kWh a day in summer. Assume you’re paying €0.18 per kWh, though you’ll want to check your actual tariff.
120 rooms × 165 days × 80% × 12 kWh comes to just over 190,000 kWh for the season. At €0.18 that’s about €34,000, and that’s cooling guest rooms only. Nothing else.
Now, if guests are away 65 percent of the time and the AC runs at their setpoint regardless, roughly two-thirds of that spend happens with nobody in the room. Not all of it is waste, because you do need the room cool before the guest walks back in. But a properly set up guest room energy management system, one that knows when the room is empty, when the balcony door is open and when the key has been used, usually takes 20 to 30 percent off room cooling.
On this hotel that’s somewhere between €6,800 and €10,300 a season, from cooling alone, before you count lighting, minibars, or the fact that the AC units stop running around the clock and last longer.
Scale it up to 300 rooms and you’re looking at €17,000 to €26,000 a season. That’s the case for hotel energy management, in one paragraph.
Seven questions to answer before you call anyone
You don’t need us for this part. You need the electricity invoices, the occupancy report from your PMS, and a quiet afternoon.
- What was total kWh and total cost for June, July and August, and how does that compare to the same months last year? Adjust for occupancy, not just the raw numbers.
- What’s your kWh per occupied room-night? This is the one number that matters. Divide monthly kWh by rooms sold that month. A well-run Mediterranean resort lands somewhere between 25 and 40. If you’re above 50, something is running that shouldn’t be.
- What did you use on a quiet day versus a full day? If the difference is small, your building isn’t responding to occupancy, and that’s the clearest sign of empty-room waste there is.
- What’s your baseload at three in the morning? Take a meter reading, subtract what genuinely has to run, and look at what’s left. Usually it’s corridor lighting, back-of-house cooling and a lot of rooms being cooled for no one.
- How many rooms had the balcony door open with the AC on? If you can’t answer that, you can’t manage it. The sensors are cheap. The information isn’t.
- When was your peak demand? Demand charges can be a big part of a commercial tariff, and the peak is almost always mid-afternoon on a changeover day, when housekeeping props open every door and every unit restarts at once.
- Which floors or wings are the outliers? Even rough sub-metering tells you where the problems are. A struggling unit, a leaking duct, a thermostat some guest left on 18 degrees in June that nobody’s touched since.
What we usually find
We’ve done this exercise with enough properties in the region to know what tends to show up:
Housekeeping resets are all over the place. Some staff switch the AC off, some set it to 22, some leave whatever the last guest chose. Across 200 rooms that inconsistency alone is worth thousands of euros a season.
Rooms cooled to the guest’s setpoint from check-in to check-out, whether or not anyone is in them.
Corridors and public areas kept cold all night. Often 10 to 15 percent of the bill goes on spaces nobody uses between midnight and six.
And the Saturday surge, where every unit hits full load at the same time and sets the demand charge for the whole month in a single hour.
None of these are equipment problems. They’re hotel energy management problems, which is good news, because management is something you can fix over a winter.
What you can actually do over the winter
An audit is only worth doing if something comes of it. If your room data shows 20 percent or more going to waste, here’s what a realistic winter looks like.
October and November: audit and baseline. Make kWh per occupied room-night your official number. Decide which floors or wings to start with.
December to February: install room control. Modern room automation retrofits are an occupancy sensor, door and window contacts, a thermostat, and integration with the lock and the PMS. No structural work. It’s done room by room while you’re closed anyway.
March and April: commissioning and training. Housekeeping learns the room now resets itself. Reception learns that check-in starts the pre-cooling, because the access control system tells the room someone has arrived.
May onwards: measure against your baseline. The first full season with room control is where the 20 to 30 percent shows up on the invoice.
Payback on a room-level retrofit in a seasonal Adriatic hotel is generally two and a half to four years on energy savings alone. Add lower HVAC maintenance, longer equipment life and the sustainability reporting that tour operators, OTAs and EU energy efficiency rules are increasingly asking for, and the numbers get better still.
If you only do one thing
Work out your kWh per occupied room-night for July. Ten minutes with the electricity bill and the occupancy report.
If it’s above 40, your rooms are spending money while they’re empty. That’s the most reliable sign we know that a hotel energy management project will pay for itself, and the winter is when you’ve got the time to do it.
Spica Hospitality does room automation and guest room energy management for hotels in Croatia and the region, built on EOS room control and integrated with Vingcard/Vostio access. If you’d like a structured post-season energy review before the winter works start, get in touch before the numbers get filed away.