* Calculation based on 8 hours of work a day and 4 weeks a month, using Endesa's Conecta Luz tariff (€0.109/kWh) and average estimated device consumption.

How to calculate the cost of working from home

The calculation in the table above can be more accurate if you measure the real consumption of the devices you use at home. You just need to follow this process:

1. Know the consumption of your work-from-home setup

Every computer has its own power rating, just like the different types of lamps and appliances in your home. That is why the best way to find out exactly how much it costs to work from home starts with checking that wattage.

For instance, a desktop PC and monitor like the one in our example, used at full capacity, usually draws more power than a laptop used for office applications and web browsing. And an air conditioning unit for a large workspace needs more watts than a small portable heater or fan.

By looking at the technical specifications of each device, you will have a starting point to know its consumption: divide its power (W) by 1,000, and that will give you the electricity (kWh) your computer, light, or any other device uses for each hour it is on.

Alternatively, for even greater accuracy, you can use a plug-in energy monitor for each appliance to see the exact kWh it is using in real time.

2. Everything depends on your time, schedules, and tariffs

Once you have worked out your equipment's hourly consumption, multiply it by the time it is left on. By adding up all your appliances and devices, you will have an idea of the total kWh that working from home adds up to each month.

However, translating that consumption into money entirely depends on your contracted electricity tariff:

• If you have a stable pricing tariff throughout the day, such as Conecta Luz, the hours you choose to work from home won't affect the cost of each kWh you consume.
• If you have a time-of-use tariff, such as Conecta 3 Periodos, you will enjoy different prices depending on the hours and days you work, with the lowest rates during off-peak periods (nights and weekends) and intermediate or higher rates during the rest of the day.

Therefore, by multiplying your total consumption by the exact price per kWh of your tariff, you will know the electricity cost of working from home.

Which part of your consumption is actually due to working from home?

That is the million-dollar question. Because, while it is true that you need your home to work remotely, not everything in your house is a work tool.

In other words: to work out the real cost of working from home, you have to bear in mind that the fridge, the router, and other appliances run all day, whether you are working from home or not. And when making your calculations, it is very useful to differentiate between these two concepts:

1. The electricity consumption of just being at home

There is the fridge, which needs to be kept on all the time, whether you open it to snack or manage to resist the temptation. There is also the lighting in the rest of the house, especially if you live with someone else. Or you might be charging your electric car in the garage, even though you aren't using it to commute. These types of expenses, which are independent of working from home itself, should be left out of your calculation.

And there are always doubts about one possible exception: the kitchen. For many, working from home means swapping a restaurant lunch for cooking at home. But others take a packed lunch to the office anyway. Consequently, the decision to include the hob, microwave, or air fryer in the equation will depend, for a realistic calculation, on what you usually do when you aren't working from home.

2. The electricity consumption of working from home

On the other hand, there is the laptop or desktop computer and monitor. The Wi-Fi, assuming no one else is using it and you have the sensible habit of turning it off whenever you leave the house. Perhaps a good sound system for your video calls, now that you don't need headphones to block out the office noise. The desk lamp, too. And, an inseparable companion during the hottest or coldest months, the climate control unit.

The consumption of these devices, which are clearly linked to your work activity, is what makes the real difference to your bill when working from home.

Does it cost the same to work from home in summer as it does in autumn?

Working always costs you energy, whatever the season. But, inevitable jokes aside, there are seasons when the cost of working from home is higher in terms of your electricity bill:

Summer and winter, the most expensive seasons for working from home

In summer, we use less artificial light, as it is the season with the longest days of the year. And that means savings. But the use of air conditioning makes the bill noticeably higher at the end of each month.

A similar thing happens in winter, when we need to heat our workspace and the temperature contrast with the outside of the house is generally even greater. Whether you use a heat pump, electric radiators, an aerothermal system, or conventional gas heating, climate control in the colder months can account for a similar expense to air conditioning, especially if you want to work for 8 hours at a comfortable temperature.

Autumn and spring: the cost comes down to your equipment

When the weather turns milder, the cost of working from home drops too. The reason is that there is less need to use climate control, meaning your electricity consumption is reduced to your work devices and lighting. And these make up a relatively small portion of your overall household expenses.

Mistakes to avoid when comparing how much you pay to work from home

Aside from the difference between the general household consumption and what is actually generated by working from home, there are other factors you should avoid mixing up when calculating the cost of remote working:

Compare the kWh consumed, not just the final bill amount

Checking your bank account might give you a clue that something has changed in what you pay for electricity. But it isn't enough. The real information lies in the amount of kWh shown as 'consumed energy' on your bill. And, if it has increased, the next step is to identify how much of that energy comes from what you use to work from home, and how much is related to the rest of the house.

Compare the price per kWh based on your tariff

In the regulated market (VPSC), the price of electricity is set daily for each hour of the following day. As a result, turning on your computer at a certain time can be around 90% cheaper than doing so at the most expensive time of day, depending on the day.

On the other hand, in the free market, you can sign up for tariffs that keep the price stable regardless of the time of day, or that set a cost for each time band of the time-of-use model (off-peak, shoulder, and peak hours).

Consequently, your tariff plays a major role in determining how much you pay to work remotely.

Compare equivalent periods

Summer has a bigger impact on your bill than spring. And if you work from home more in some months than others, comparing them isn't very helpful. Avoid this mistake by choosing carefully what you want to compare:

• A month commuting to the office versus a month working from home?
• One work schedule versus another, if you have a time-of-use tariff?
• One amount of working-from-home hours versus another?

A simple way to make these comparisons is by accessing the Customer Area, if your electricity is with Endesa. From there, you can quickly check your billing history and the breakdown of your daily consumption.

4 tips to reduce your electricity costs when working from home

Make the most of natural light at home

Sunlight is free. If you choose a well-lit workspace in your home that gets plenty of natural light, you will accumulate small daily savings on your bill.

Monitor the consumption of your computer and peripherals

Unplug everything you aren't using, including chargers that are left plugged in, drawing vampire power. This advice also applies to how you use your computer: music you aren't listening to or a video you aren't watching makes the device consume more energy.

Pay special attention to climate control

Moderate the number of hours you have your air conditioning or electric heater on, avoiding drastically raising or lowering the temperature and using eco programmes whenever possible. You can also combine them with more affordable solutions, such as using a fan or installing thermal curtains.

Adapt your electricity tariff to your working hours

Compare and decide. If you only work from home one day a week, changing your tariff might not be necessary. But if you have noticed that your working hours clearly impact your bill, there is almost certainly an alternative that can help you start saving.

Frequently asked questions about working from home and electricity consumption

How much does a computer consume over 8 hours?

It depends on the computer, the monitor, and the applications you use. A laptop can consume between 50% and 85% less than a desktop PC with a monitor, but this dynamic can flip if your laptop needs a lot of power for tasks like professional video editing.

How much does it cost to work for a day?

The cost of working for one day is the sum of the consumption of all the devices required for your work, multiplied by the price per kWh of your contracted electricity tariff. As an example, combining a PC, monitor, router, LED lighting, and climate control for 8 hours, we can estimate an approximate consumption of less than 90 cents a day, based on the stable pricing of the Conecta Luz tariff. 

Which consumes more, the computer or the air conditioning?

Air conditioning consumes more and is, in fact, what can have the biggest impact on your bill when you work from home. The difference is clear when comparing the 100 W of power a professional laptop might draw against the 900 W an air conditioning unit uses to cool a relatively small room.

Does the router consume more because you are working from home?

Yes, although it makes a negligible difference to your bill. A home router might consume around 0.005 kW per hour and reach 0.02 kWh during peak activity, meaning a difference of barely €0.0016.

Does my company have to pay my work-from-home expenses?

Yes, although the exact arrangement depends on your specific agreement. Article 12 of Spain's Remote Working Act (Ley 10/2021) recognises the right to have work-related expenses compensated by your employer, the mechanism for which may be determined in collective agreements or contracts.