Eco-Friendly Rentals: The Money Saving Advantages Of Smart Home Technology

Introduction

Thankfully, more often than not, my holiday rental guests are respectful and mindful of their energy usage, understanding that they should do their part in conserving it. However, there have been occasions where I’ve received visitors who seem to feel like they should use as much power as possible without consequence merely because an all-inclusive fee was paid for the duration of their stay. This type of behaviour is both costly and environmentally irresponsible – which makes it particularly disheartening to witness!

Most holiday properties have summer and winter pricing: the nightly rate paid by the guest is typically a lot lower in the winter months than in the summer. However, the cost of running the property due to the additional expense of heating it can make the winter months way less profitable: possibly to the point where it’s not worth opening.

It just takes one guest to turn the heating up and then open a window or two, and the costs can be astronomical!

Holiday let groups are awash with owners facing similar issues:

What’s the Cause?

Human nature and (bad) habits!

I’ve probably spent too much time thinking about why it happens, but I concluded that it is because of how we all control the temperature in our cars.

Consider this: when you get into your car on a cold morning, do you gingerly adjust the temperature gauge a little higher, or do you go straight round to max? You go straight round to max, don’t you? I bet the equivalent is true when you get into a hot car: if there was sub zero on the gauge, that’s where you’d turn it to.

Once the car has warmed up or cooled down, we move the dial to a more appropriate setting. The dial is right there in easy reach, and if we stop driving before that point, it won’t matter anyway.

For those guests who are so inclined, it will not matter if there is a temperature dial, button or screen to type the desired temperature into; they’ll not bother – for them, there are only two necessary settings: full max or full min.

Won’t they move the dial to a more appropriate setting when they’re comfortable?

Maybe.

However, what you also have to bear in mind is that they are likely to be staying because they are on holiday and are probably out and about: they’re a bit cold, switch on the heating, then go out.

I know because I have the evidence to back it up that guests will set the heating as high as it will go and then leave for the day. They’ll return to a roasting hot property and open all the windows – without necessarily adjusting the thermostat!

This is bad for the planet and bad for my energy bills!

To stop this needless wastage, I’ve implemented Smart Home Technology in my holiday properties, and it has made a huge difference.

How are my properties heated and/or cooled?

My city centre holiday apartment is heated with individual electric heaters (there is no gas in the building).

My holiday cottage is heated with gas central heating.

Both have electric ovens and electric showers.

Neither has air conditioning, although everything I write about could apply to air-conditioned units.

What can Smart Home Devices sense?

A surprising amount.

Firstly, I want to clarify something. These devices are blind and deaf. They have no audio, photo or video capture/transmission capability.

The devices measure such things as:

• ambient temperature
• mains voltage
• immediate power usage in Watts
• ongoing power consumption in kWh
• overall brightness
• door/window open or closed (via magnetic sensor)
• smoke
• movement (via passive infrared (PIR), the same as used by your home alarm system)
• carbon monoxide
• humidity
• presence of water (leak detection/water ingress)
• wind strength
• rainfall

The electricity sensors are clever enough to know which way the power flows, so if you have solar panels or other renewable energy sources, the data will be correct.

When do they act?

Thresholds can be set to trigger when a data reading goes below or above pre-determined levels. Examples of thresholds:

• temperature higher or lower than wanted
• number of kWh of electricity is higher or lower (think about freezers) than pre-determined levels over a particular time scale
• mains voltage high or low
• door/window open (or open for a certain time)
• humidity higher or lower than wanted
• movement, or lack of movement over a certain period
• Smoke / Carbon Monoxide detected
• Water / no water detected

What can they do?

These devices’ data can then be used for informational purposes and direct, automatic control. Examples of automated control:

• turn a light on or off (or even flash, which helps wake sleeping people or for those hard of hearing)
• run/stop an extractor fan
• cut the power to a heater
• run or shut off the central heating
• run or shut off the air conditioning
• lock or unlock a door
• open or close a garage door
• open or close curtains
• make a ptz camera point in a particular direction
• set the temperature of the Thermostatic Radiator Valve (TRV)
• sound an audible alarm
• actuate a lever to cut the mains water or gas supply

Examples of automated information:

• send an alert via email/Telegram/WhatsApp/SMS/pager, etc
• trigger a webhook
• log data
• populate a graph

What have I installed?

Power Meters

Power meters tell me the overall power consumption of the properties

Power relays

I have installed power relays on each of the heaters. These power relays do two things: they allow me to remotely power the heaters on or off, and they record how much power is being consumed.

Window / Door Sensors

I have installed sensors which tell me if the door or window is open/closed

Temperature Sensors

I’ve installed temperature sensors and/or room thermostats with temperature sensor

Boiler Control

The boiler only runs when all windows are closed

What do I do with the information?

Graphs

I graph the data, which tells me a huge amount of information about the property:

Summer Power Usage:

Winter Power usage is very different:

You can see how the majority of the power was consumed by the heaters and how changes made by guests has a dramatic effect on consumption:

Automatically prevent wastage

At the apartment, I have programmed the system to automatically cut the power to the heater in that particular room if the window or balcony door is open for more than 5 minutes. When the system detects that the window/door has been closed for 2 minutes, it powers the heater back on.

I want my guests to be comfortable, but if the temperature goes over a certain level, the power will cut automatically, as can be seen in the graph above.

At the cottage, the boiler will not run if any of the main windows are open.

Illicit/illegal activity at the property

If your holiday let has been booked for use as, for example, a pop-up brothel, the occupants will probably want the rooms fairly warm. They might also want windows open between visitors to freshen the air. This combination of open windows and heaters on can be very costly for the holiday let operator. Although far from conclusive in its own right, this information could alert the holiday let operator to a developing issue possibly involving vulnerable people who have been coerced into that type of work.

Electric Vehicles

An issue cropping up more and more frequently for holiday let operators is guests arriving and plugging in their electric vehicles to recharge. This causes several issues for the holiday let owner/operator

Health and Safety

If the property has not been set up with a dedicated charge point, the guest might get creative with running cables out of windows / cat flaps, etc. This creates a trip hazard which the holiday let operator is potentially liable for.

The cable used might not be up to the task of delivering that much energy for a sustained period of time. Underrated or damaged cables heat up, which can lead to fires.

The electrical circuit within the property that the guest chooses to plug into might not have sufficient capacity.

There have been fires and product recalls due to this happening.

The unexpected cost

The holiday let operator is very unlikely to have included the cost of charging the guest’s electric vehicle(s) in the price of the stay. A guest would not normally expect the operator to accompany them to the petrol/gas station and pay for a full tank of fuel – why should the operator pay for the electricity to the EV unless it has been pre-agreed?

Security

If the cable is draped out of a window, that window is not locked and is therefore at greater risk of an intruder breaking in.

How Could a smart home help?

The simplest installation of just a Smart Home controller plus a clamp-on power meter with the appropriate configuration would allow the holiday let owner/operator to be notified automatically if the property’s power consumption increased due to the plugging in of an EV.

I monitor the power consumption at my home and can produce graphs for any given date range, such as December 2022:

My sister and her family joined us for Christmas, and they plugged their Volvo hybrid car into a standard plug socket, all by agreement, I should add. Even though the hybrid car does not have as much battery capacity as a fully electric vehicle, you can still see the significant consumption spikes that it caused on Friday and Saturday 24th.

Looking at the daily graph, the solid block of blue stands out as exceptional consumption:

When new holiday guests arrive, a cursory glance at the power consumption graph after 24 hours would show whether they were using a “normal” amount of power or whether further investigation was necessary.

Heaters with inbuilt open window sensors 

Most modern, energy-efficient electric wall heaters will have an automatic function to save money called an open window sensor. This ingenious little device will detect when a window has been opened in the room and automatically turn off the heater.

The sensor is usually built into the bottom of the heater. When you open a window, the cold airflow across the sensor will cause it to trip and turn off the heater. The reason is simple. If a window is open, then the heat will escape, and there is no point in the heater continuing to run. The sensor will also turn the heater back on automatically when the window is closed.

For this to work, you will need one heater per room, which must be installed according to the manufacturer’s instructions.

You might think this is foolproof and would work fine in a holiday let situation. The reality is that an open window sensor alone will not provide any meaningful protection. The reason is simple: if a window is opened, the temperature drops, and the heater switches off as designed. If the temperature never rises again, what does the heater do: does it stay off forever? No, it can’t stay off forever. After half an hour or so, it assumes the new temperature is the new ambient temperature, and it must try to correct it by heating the room at great expense.

You will only get meaningful protection and save energy with your heating system if you have a sensor which knows definitively if the door/window is open or closed.

What equipment and technologies do I use?

The smart home technology I have implemented comes under the banner of Z Wave. Z Wave is the communication language and radio frequency the devices use to link themselves.

The smart home controllers I use at the moment (I am planning to switch them up in due course as they are somewhat outdated) are Vera Edge controllers, which can be picked up on eBay for not a lot of money (£20 or so if you’re patient).

There are various sensors throughout the properties, many of which can be purchased quite cheaply if you find them on eBay.

Vesternet is an excellent supplier of new home automation equipment – sensors and modules (the bits that do the work)

Various scripts run on the Vera controller to take appropriate action when thresholds are reached.

Every 150 seconds, a script gathers all the variables and transmits them to a cloud server.

I wrote a basic API in node.js to sit on the cloud server to receive, process and store the data.

The graphs are produced by rrdtool, and are populated by data which is stored in rrdtool databases

Weather data feed from OpenWeather

Conclusion and clarification

My properties are effectively on autopilot. They are set up so that I don’t have to be there to manage them, and even though I can look at graphs, I don’t have to. They will automatically save energy by shutting down devices and the heating system as necessary.

Graphs are, in my opinion, the best way of understanding what is normal for a particular property. When something abnormal or unwanted happens, it will stand out to you – you will spot it on the graph and can take appropriate action.

I have set things up so I can track what is happening in each property, no matter where I am.

In addition to the smart home devices, I have done all I can in other ways, such as installing energy-efficient lighting throughout. Both properties have a smart meter, which only gives an instantaneous readout and benefits the utility supplier.

Guest’s usage of the utilities is normally a great unknown for holiday let companies. As well as reducing energy consumption, reducing my carbon footprint, and protecting the planet, I’m confident that I can protect myself against unnecessarily large utility bills, which means I can pass the savings on by way of lower occupancy charges.

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