The Energy Certificate of an Apartment in Portugal and How It Benefits Renters

The energy certificate of an apartment is a document that details the apartment’s energy efficiency, pointing out problematic areas and how to improve them. The higher the energy efficiency level, the better the apartment maintains its temperature without exchanging heat with the surrounding environment. Simply put: it keeps warmth in during winter and prevents heat from entering in the summer.

The numbers in the certificate are based on the effectiveness of heating the apartment, cooling it down, and heating water. The actual values are expressed as a percentage compared to a target value. The result places the apartment into one of six categories, from A to F.

All energy certificates have letters ranging from A to F, from the best to the worst. It’s similar to the energy ratings you see on refrigerators and washing machines. Just knowing the letter can give you a good idea of how warm the apartment will be in the winter and how comfortable it will be in the summer. In general, I’d recommend looking for apartments with certificates B, C, or, at a stretch, D. While an A rating does exist in Portugal, it's extremely rare and usually only found in newly built properties. If you see an A rating in an ad for an older apartment, it's likely a mistake or a scam.

If you rent a place with a B rating, it means you can walk around in long sweatpants and a t-shirt in winter without freezing. The apartment won’t cool down too quickly after you’ve heated it to a comfortable 22º-23ºC.

A C-rated apartment will be a little cooler. You might wake up in the morning to a room that’s around 20ºC — it’s not unbearable, but you’ll need warm pajamas and socks to get out of bed. If the certificate is D, be prepared to have a cold nose when you wake up, as the apartment will have cooled down a lot.

You can still rent an apartment with a D rating, but you’ll definitely need heaters, warm clothes, and blankets.

Even if the apartment has a low rating, it’s not the end of the world. You can request the full certificate and look at the report to see exactly where the energy is being lost.

The certificate will show energy losses in winter (on the left) and summer (on the right). This allows you to come up with strategies for making the apartment more comfortable.

For example, if energy loss occurs through the windows, you can hang curtains to help maintain the temperature. It’s also essential to close the shutters (external blinds, known as estores in Portuguese) before bedtime to keep the warmth you gained during the day. During the day, open the shutters to allow the sun to heat up the apartment. If energy loss occurs through the floor, consider buying a rug to minimize losses.

In conclusion, the lower the certificate rating, the higher your electricity costs will be, as you’ll need to constantly maintain a comfortable temperature. If the apartment has air conditioning, that’s better than using electric heaters since air conditioners are more energy-efficient. Heating with an air conditioner is generally cheaper than using a regular heater, especially if the AC has a heating function. If the apartment doesn’t have AC and the certificate indicates that installing one would significantly improve the apartment’s energy efficiency, try negotiating with the landlord to have it installed.

For example, in this certificate, it mentions that installing air conditioning (point 3) with a heating function will immediately raise the apartment’s energy efficiency from F to C. If I were the tenant, I’d definitely consider this: the estimated cost is €2500, and the savings could be up to €560 per year. It would pay off in about 4.5 years.