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How does the orientation of housing influence energy consumption?

The orientation of the main facades of our home influences the temperature that, in turn, determines how much energy we will need to consume. Knowing which way a house faces, especially if we are about to buy or renovate it, is key to saving money on our bills.

The orientation of your home greatly conditions its air conditioning. This topic concerns you because keeping your home at a comfortable temperature is the most important part of your energy bills. What each appliance consumes comes second in this ranking of expenses, followed by hot water and lighting.

That is why, if you are thinking about carry out any work, or if you are looking for a new home, you should consider which way the building faces. What it will cost you to find the right temperature for your home depends on this apparently trivial data.

To better guide you, we will use the data from the IDAE efficiency and savings guides at all times (For guidance, we will use the efficiency guidelines of the IDEA (Institute for Diversification and Energy Saving).

"The most important part of your energy bills is heating or cooling your home depending on the season."

Is the orientation of a house so important?

The short answer is yes, an emphatic yes.

You know what the long answer would be, but maybe it is not something you think about when choosing a home. The sun rises in the morning and heats buildings in very different ways:

For example, facing East, a house is heated in the morning and cooled during the rest of the day. Ideal if you work during a standard day and live in the south, so you will find that your home is fresh when you return from work. Also perfect for those who work at home in the mornings in climates that are not hot.

However, this same orientation can be a nuisance in summer for someone from southern Spain whose bedroom is just behind an east-facing facade. Such a wall will let out all the heat it has absorbed during the day and will release that temperature in the bedroom during the evening, which guarantees a warm night.

In other words, your house’s orientation determines the solar radiation it receives during the day, and the way in which it is transmitted to the house’s interior, for better or worse. Given that most of the energy bill (electricity plus gas) is due to home air conditioning, it is worth knowing about the relationship between energy consumption and orientation.

The importance of orientation in Spain

Although there are significant changes in temperature between our country’s different regions, with a warmer climate further south and with shorter and colder days the more north we go in our geography, there are a number of generalisations that will help us to understand the importance of the orientation of our main facades:

  • East-facing facade. It is the first side to receive light in the morning, as the sun rises along the ecliptic (the curve that it traces as it crosses the sky). Although to a certain extent it is heated in the morning, the truth is that after noon the facade tends to cool as it does not receive direct radiation thereafter. Cold nights.
  • West-facing facade. Unlike the East-facing facade, it receives light from noon to dusk, and it is one of the directions along which the largest amount of total radiation comes, especially in southern Spain. It tends to get very hot throughout the afternoon, and such heat remains during much of the night. Warm nights.
  • South-facing facade. The facade that receives the most radiation of all, especially in the north of the country. If there are no buildings in front, the light enters from early morning until sunset, and therefore it is a facade that tends to get very hot. Without curtains, the floor will gain a lot of heat during the day. Very hot nights.
  • North-facing facade. It is the coldest orientation of the house. In Spain, a north-facing facade does not receive direct solar radiation (only indirect radiation, from the clouds) and it is also the facade through which we lose most energy throughout the day. It is the house’s cold focus, and the one that will first have to be insulated for winter. Pretty cold nights.

 

Are you looking for a house? Look at its orientation

It is possible that some readers are looking for housing (for those who are not, they can go to the next point without any problem) and wondering what the optimal orientation is in their region. On the one hand, it is in our interest that in winter the sun heats our home for free, while in summer we prefer that our house is shaded. Unfortunately, the winter sun is low and the summer sun is high.

This means that we will have to choose. For example, if we buy a house that is low lying, it is unlikely that we will receive any sun in winter from the south (because it will be covered by the houses in front of it), while it is very likely that in summer we will receive a good dose of radiation directly from above. Unless, of course, we have trees in front, something that helps a lot in hot climates.

In general, in the north of Spain, South and West-facing orientations will interest us as they will enjoy a lot of sun all year long, while in the south, East and North-facing orientations are highly sought after. Even so, a house with two orientations (north-south or east-west) may be a very good idea to facilitate cross ventilation, especially for cooling in southern Spain.

A very interesting compromise solution is the following: a house with a south-north orientation, with very good insulation on its north-side and with passive elements built on its south-side, such as horizontal eaves, canopies, static louvers or shading devices. In this way, we will have sun in winter with only a little energy loss through the north-side, and shade from the facade in summer.

"In the north of Spain, people look for South and West-facing orientations while in the south, the most sought after are orientations that face the East and North."

How to orient the interior of a house

But now suppose that, as will often be the case, we do not plan to move house to save on air conditioning or lighting. What we can do is change the use of the interior of the house so that we save on heating and air conditioning depending on the type of facade we have. For this, imagine a typical home with a kitchen, a bathroom, one or two bedrooms, a living room and a study. Where is it best for us to locate each room?

There are areas of the house that do not need heating, such as the kitchen and bathroom, or whose climate control will be occasional (when showering). If these rooms are positioned to the north or east, leaving us the south and west for the living room and the study, it will make it easier for these two rooms to heat up naturally throughout the day. Bioclimatic principles.

in their purest form.

Leaving the cold rooms to the north and the warm ones to the south will help us avoid turning on air conditioning and heating, at least to a certain degree or for fewer hours per year. Even if we work at home and make use of the studio, or if, in southern Spain, we spend time in summer in the living room, locating it facing south may be a good idea, leaving the bedrooms to the north.

This is due to the fact that heat does not pass directly into the interior of the house but instead accumulates in the walls (thermal mass), and then moves towards the interior over the following hours. This is known as thermal inertia, and that is why we will feel hot at night in a room facing south even if it is not very hot outside: the wall radiates the heat absorbed during the day.

 

Is it worth carrying out building work to change the distribution of our housing?

Although many homes have been built following these basic principles of bioclimatic architecture, the truth is that not all of them have taken this into account. Thus, we see rooms to the north that stay cold all day and rooms to the south where we need to put the air conditioning on for many days a year. If we are refurbishing, carrying out extensive building work, it may be a good idea to propose a change.

As we mentioned at the beginning of the article, more than half of the gas and electricity bill will be spent on climate control. This is even more true regarding houses, as opposed to flats, since house owners spend approximately double on climate control because the walls of houses are more exposed to the outside. So, to do the maths, we can check if a saving of between 20 and 30% in energy consumption (consumption, variable part) merits paying for any such refurbishment.

If, in addition to changing the distribution of the home, we improve its insulation (windows, thermal breaks, awning installation, etc.), these percentages will increase. The more years we are going to spend in the same house, the sooner we will be interested in optimising its use with regards the orientation of the four points of the compass.

And, if it is impossible for us (it is not easy to change the position of the pipes), we can always follow the trend in passive housing In many cases, changing the orientation of the rooms or planning a move is absurd, so we will have to optimise where it is viable.

 

The importance of natural light

This article has taken into account the highest energy expenditure of all: air conditioning. However, there are other energy expenses to consider. Namely, a house facing south or west will not consume electricity running an electric dryer, more will be spent on the refrigerator in a kitchen facing south, and a north-facing house will consume more electricity in lighting.

Although considerably less than other items, especially thanks to LED bulbs, let's not forget to maximise natural light, especially due to the relationship between lighting and our health Leave the rooms we spend more time in to the south and west, especially if we work at home or come back before the sun goes down, respectively. They will decrease electricity consumption and help us to live in a less artificial environment, something that our metabolism will appreciate.

"In a South-facing kitchen, more money will be spent on the refrigerator, but very little on the dryer."