There is no shortage of articles online telling you how to save money when you build a house. This one goes the other way. These are the things you should not save on when building a house in Spain — the upfront costs that quietly pay you back for the next thirty years.
I am too poor to buy cheap is a German saying that makes a great deal of sense. The Germans take the view that the things that matter — your shoes, your coat — have to be good, so that they do their job and last a long time. The British version is shorter: buy cheap, buy twice. Let us apply that to a house.
Spend on a good design
You may think I am talking my own book here, and fair enough. It is still one of the points I am most certain about. A good design anticipates future extensions. It sets out the structure so that every window and every external door can be a standard size instead of made to measure, which is money saved before a single block is laid. It separates day zones from night zones — and the guest wing from the rest — so that the services can later be split into independent circuits. It gets the geometry right, the orientations right, and uses passive climate control where the site allows it. And it does not carry the errors that turn into serious cost overruns halfway through the build. An architect’s full design package normally costs less than 5% of what the building work costs, and against a cheap set of drawings that is unoptimised or full of errors it can save you many times its own fee. The drawing is the cheapest place to change your mind.
Spend on energy efficiency
On the services side, a decent set of solar thermal panels for hot water recovers the investment through lower electricity bills in under five years, and from then on you are simply spending less. Services split into proper zones let you shut down the parts of the house you are not using: if you have a guest wing, it should sit on its own circuit that you can close off. It costs a little more at the start and then saves for the life of the house. The same goes for heating and cooling — zoning it by use and by orientation is fundamental. You can use a system such as Airzone, but the real key is a good services design. There are houses where one room is hot in the afternoon because it takes the sun while another is cold at the very same moment. The installation has to have anticipated that, so you can cool one space while heating another, and leave the rooms you are not using alone. Photovoltaic panels also pay for themselves over time. As the rules stand as I write this, you have to feed what you generate into the grid and sell it to the supply company. If households are one day allowed to store that energy and use it at home, that will be a genuine revolution.
On the construction side, use systems with good insulation that eliminate thermal bridges, and then audit what has actually been built with a thermographic camera or a Passivhaus-style pressure test. External wall insulation is where the money goes furthest. In Spain you will hear it called SATE: insulation fixed to the outside face of the wall and rendered over. Pair it with good windows — thermal break, sealed cavity, low-emissivity outer pane. All of that costs more on day one and then amortises steadily. After payback it is all saving. Do check the low-e pane has gone in the right way round, mind. You see everything on a building site.
There are also systems that do not merely keep heat and cold out, but let outside energy in when it suits you, or even provide cooling. A Trombe wall is one example. A greenhouse effect on the outer face heats a thick ceramic or stone wall of low transmittance. The energy is gathered during the day and reaches the house at night, because it takes a full day to travel from one face of the wall to the other. For the opposite case — cooling rather than heating — there are blue roofs, which insulate and also let you circulate air moved by solar chimneys. A solar chimney has metal elements on the outside that heat up and warm the air inside it; warm air rises, that movement pulls the rest of the air up the chimney, and you have ventilation. Run that air over water at a lower temperature and it cools; bring it out inside the house and you are cooling the interior.
Fit systems that use little water and reuse what they can
Another meaningful saving comes from fittings that keep water use down, that reuse greywater, and that even collect and reuse rainwater. On this coast, with the summers we have, none of that is eccentric. Over the life of the house it pays for itself.
Plant deciduous species
Deciduous planting shades the sunlit walls in summer and keeps out a great deal of solar gain. Then the leaves drop, and the same energy comes through in winter when you want it. A very good solution, and not a dear one.
Ventilate
It sounds like advice from your grandmother. It is not. Make sure the design provides for cross ventilation, and that you can shut it down in winter so you are not throwing energy away, then open it up in summer to ventilate and take the edge off the temperature at no energy cost at all. That is a serious source of saving.
Go carefully with termoarcilla
Termoarcilla — the large-format lightweight clay block used across Spanish housebuilding, and something most buyers arriving from northern Europe will not have met before — is an excellent system with real virtues. The units are big, so the walls go up faster, and it has very good thermal and acoustic insulation. My only warning is this: if you go for it, have it laid by people who are used to laying it, and insist on the purpose-made units at corners and reveals. It is very common to see bricklayers misuse termoarcilla simply because they do not know it. They finish corners, lintels and reveals with ordinary brick, or with broken pieces of block instead of the purpose-made units. That builds thermal and acoustic bridges straight into the wall.
Plan the build properly, and pay someone good to supervise the contractor and the trades
A building site is a lot of separate work streams running over one another. Some things have to happen before others — services before plastering — and some are a bottleneck for everything else: once you have poured concrete you have to wait before you can work on the storey above. A well-designed programme optimises all of that and saves you a lot of money. If you are self-building, do not save on designing that process; hire a good project manager. If you hand the construction to a contractor the programme is not your responsibility, but you do need a professional of your own checking the quality, checking the dates, and checking that what is going up is what was drawn. In Spain that job belongs to the dirección facultativa: the architect and the quantity surveyor (aparejador) who supervise and sign off the work as it is built, and who answer to you rather than to the builder. This is another cost that is not worth saving, because good supervision saves you more than it costs.
Conclusion
There is a great deal more one could say, but I will stop at those examples and one general idea. When you think about the whole service life of the house — not just the initial investment, but the monthly bill, the annual and multi-year maintenance, the durability — the perspective changes.
Some things are not an expense but an investment. Those are the ones worth spending on.
