In Spain we have a cooling problem in the summer. If you’re from Northern Europe don’t underestimate this. In July and August it can be, quite simply, too hot. #healthyhousedesign
In winter, spring and autumn temperatures can vary widely even in the course of a single day. When the sun is out you can be in shorts, even in the winter, and on the same day, in the evenings, you may need a coat or a jacket.
It may even be desirable at times to have cooling in one room and heating in another. Our client in Salobreña can have heating at the back of the villa, North facing, where it may be cold, and cooling at the front of the villa where in the sunshine it may be too hot.
So we need healthy, “sustainable” cooling systems and we also need flexible fast response systems.
What do we mean by healthy? Let’s say a healthy cooling system is healthy for you, healthy for your bank balance, and healthy for the planet.
Let’s look at the options:
Conventional Air Conditioning: These can be either wall mounted units or pre-installed with ducting. They emit cool air into the room. They are fast response and that’s good. However, these systems may inadvertently circulate the bugs and impurities in the air and harbour bacteria. In any case the filters need cleaning regularly. If they are run on grid electricity, and if that is sourced from fossil fuels, then they are not good for the planet. They are expensive to run with electricity costs rising.
If you use these they should also be quiet and not create a continuous background hum that can inadvertently create stress.
Renewable Energy Sources If you use any kind of renewable energy system then your conventional air conditioning is green. Renewable energy systems include air sourced heat pumps, that are straightforward and quite common, or ground source heat pumps, sometimes called geothermal. Other sources are photovoltaic electricity or wind generated electricity.
In terms of the health of your bank balance while there may be some initial additional costs of investment payback periods are falling as the costs of the installations fall and the cost of grid electricity rises.
Closed Circuit Indirect Evaporative Cooling: A few years ago I investigated a cooling system that was being developed by a highly entrepreneurial company based in Madrid. The idea seemed perfect: almost zero running costs (post installation), no electricity usage, no noise, and the hotter outside the cooler inside. This is a brief explanation of how it Works…………
Imagine two sealed chambers connected by a pipe and a tap which allows you to close off that pipe. There is salt in one chamber and water in the other. What you do is heat the salt which dries out forcing the moisture into the water chamber. Now close the tap connecting the two chambers and stop heating the salt chamber. In fact allow the salt chamber to cool, and you have stored a cooling potential. When you open the tap, the water chamber will cool as the water evaporates and seeks equilibrium with the chamber of salt. You can use this cooling effect to cool water in pipes which you can use to cool the building.
In practice this system method has potential in commercial situations but not really for domestic situations. This is partly because of the expense of installing the system. Also I seem to remember a problem is that it works well when the outside temperature is very hot but isn’t so good when it is just a bit too hot which is the case a lot of the time.
Under floor Cooling: Underfloor cooling can use the same tubing as you use for underfloor heating. Under floor heating is probably the most comfortable of all heating systems because it is radiant. Underfloor cooling is also effective with a few cautionary notes.
There is a danger of condensation if the humidity levels rise too high.This can be controlled with a system that automatically shuts down the underfloor cooling when humidity levels rise above a certain level.
Ideal Combination An ideal design would also incorporate conventional air conditioning units that engage when humidity levels rise. This has two effects. The conventional air conditioning units take over the cooling job and they also lower the humidity.
You also have both a fast response system (conventional units) and the comfortable system the underfloor cooling.
The disadvantage is the expense and complexity of the system.
I might also add anecdotally that my wife has a fear of cold feet and doesn’t like underfloor cooling for that perfectly good reason.
Earth Tube / Canadian Well This is a very simple elegant solution and is also passive. I use the word passive in this context with reference to passive design principles that minimise mechanisation in house design especially the heating and cooling methods.
It works very simply. Even in the summer months and even in hot countries the earth a few feet underground is cool and constant. So, in the simplest version, you bury a long pipe underground where the air inside the pipe is cooled and, using a small fan, you gently blow the cool air into your house.
It’s natural, passive, and inexpensive.
Obviously the specification needs to match the size and design of your house as well as the local climatic and ground temperature conditions. Needless to say given the heat in Southern Spain in the summer such a system may need some “active” back up.
Shading and Orientation Any discussion about cooling systems in Spain has to cover orientation and shading. Any unshaded south facing window in Spain will almost guarantee that the room behind it will over heat in the summer. Even if you have triple glazed argon filled e-coated glass and air conditioning. The sun is just too powerful. So avoid that at all costs.
Also be aware of the problem of west facing orientation. These may be great in the winter but in the summer evenings when the sun is low in the sky it is hot and it will come under any shading you may have installed outside such as a pergola. Your only option is to block it in which case there is no point in having the view or natural light or whatever advantage the orientation affords.
So an energy efficient / comfortable design must include thoughtful decisions regarding the orientation and methods to control the sun which might include retractable awnings and / or shutters. Please don’t think that have curtains inside the window is any kind of solution.