How to heat and cool your home effectively and efficiently

Being effective means achieving your objectives. Being efficient means doing it with minimal resources. It is a very obvious difference and there are endless ways of being effective but very inefficient. One example of this is a private jet, which can get you from A to B in a flash, but burns through so much fuel that we inevitably choose more efficient means of transport.

And while we are on the subject of the electricity you use at home, how about the old incandescent light bulb. This old-fashioned type of light bulb has been banned since 2012 Are they effective? They sure are. They give off a lot of light and they work at full performance from the second you turn them on. Are they efficient? They are terribly inefficient, because five percent of their emission is light and the rest is heat.   

"Effectiveness is achieving an objective. Efficiency is consuming minimal resources to do so."

There are numerous options available for cooling and heating your home. Heat comes with electricity or fuel, such as gas or pellets, and there is much discussion about what works best for heating. In contrast, there are fewer alternatives for cooling your home: either air conditioning or passive systems like awnings and bioclimatic (geothermal) construction.

How would they rank on an efficiency and efficacy scale? We’ve listed them according to their overall scores. 

Geothermal: energy from the earth

The geothermal mechanism is quite simple, although installing these systems is rather expensive, involves major construction work and is not suitable for all homes. The idea is to draw a stable temperature from underground, where there is a constant temperature close to 15ºC. Ducts are used to capture this energy.

In summertime, 15ºC is cool compared to the outside temperature, so it is used to keep the home cool. Different gases or liquids are pumped that become cool underneath our feet and are warmed up by the air in our home as they rise. The opposite happens during the winter, and the system is often supported by a heat pump that helps to increase the temperature from 15ºC with a compressor.

• Advantages: effective and efficient. Geothermal systems are among the most effective and efficient ways to heat and cool the home, particularly when used with underfloor heating and passive systems supported by heat pumps. The comfort level is very high, and electricity consumption per kWh of heat and cold is one of the lowest possible (approximately 0.033 euros / kWh).
•  Drawbacks: complicated and costly. These systems require major construction work to build a well under the home. This is very costly and it will take a long time to pay for itself. Malfunctions are expensive to remedy. What’s more, not all homes are candidates for vertical wells because of public infrastructure like sewage systems.

"Geothermal energy is amazingly effective and efficient… but digging a well under your property is expensive, cumbersome and not always efficient."

Aerothermal energy: energy from the air around us

We mentioned heat pumps when we talked about air conditioning, which are among the most efficient systems invented. When the machine is in heat mode, is very easy to visualise what is happening. Just imagine a heat conveyor belt. In effect, that is what a refrigerant gas tube is. When in heat mode, aerothermal energy production works like this:

1. The aerothermal refrigerant circuit captures heat from the outside air (0ºC is technically “heat”).
2. A compressor compresses this gas, raising the temperature.
3. Once in the house, the split acts as a heat exchanger, releasing it inside and cooling the coolant.
4. It goes back outside, where it expands and gets much cooler.
5. And the cycle begins again: the coolant heats up, is compressed, and goes inside. And so on and so forth.

In cooling mode, the circuit goes the other way. The coolant is heated by the heat inside the house. It is compressed to heat it and taken outside, where it is cooled by releasing heat into the area, and then it expands, cooling even more. Once it is cool it comes back inside, where it can capture more heat from the air.

• Advantages: super efficient. One of the most efficient machines that exist. The European Parliament declared it renewable energy for its performance. Each electric kWh of consumption releases between 3 and 7 kWh of cold or heat inside. It can be installed through ducts or through splits, dividing the house into sections. And with no radiators, you gain space.
• Drawbacks: it isn’t suitable for everyone. The machine inside is usually bulky and installed on the ceiling, so ducts can lower the ceiling height and require renovation. Although more expensive to install than a boiler, it pays for itself in fewer years. These systems can produce unpleasant vibrations if improperly installed. They are not recommended for extremely cold climates. You need an electric water heater.

"Aerothermal systems are effective and super-efficient, although they do involve some installation there are other drawbacks."

Air-water aerothermics: getting the best from your radiators

Although air-water aerothermal systems should appear after geothermal systems in this list, we are putting it here to make it easier to understand. Air-water aerothermal technology is similar to air-air technology, but instead of exchanging heat and cold using the air inside the house, a closed water circuit is used. This makes it very efficient and effective, because there is a tank.

• Advantages: very effective and very efficient. The second-most-efficient system on the market, and a vast improvement on the performance of air-to-air aerothermal energy, and with consumption of 0.045 euros/kWh. Unlike air-air aerothermal, it does produce domestic hot water. You can use your existing gas radiator circuit, greatly reducing the installation price. It consumes very little and pays for itself quickly.
• Disadvantages: the machine is expensive. The machine can be very expensive, particularly if you remove your radiators and install underfloor heating (more comfort), so there is an initial outlay This is particularly true if you choose machines with an A+++/A++ label (hot and cold, respectively). You need several closets around the house to install components, which take up more space than a boiler or electric water heater.

"Air-water aerothermal systems are very effective and efficient, although the initial outlay can be high."

Gas boiler: moderate cost and stability

A gas-fired HVAC system, which requires a heat pump for air conditioning in summer but does not need an electric boiler for hot water, is particularly suitable for cold places due to the way it heats: burning fuels such as natural gas. It is a low-efficiency, but highly effective machine.

These thermal systems are available at a reasonable cost. The cost of buying and installing a gas boiler is moderate, and the cost per kWh was around 0.063 to 0.086 euros in 2019, depending on the fuel (natural gas and diesel C, respectively). It is in the middle segment between the most expensive solutions and the cheapest in the long term.

• Advantages: no renovation work is required. It uses thermal radiators, already installed in many homes, so it does not require any renovation work. The purchase price is moderate. Its inertia system (it takes time to reach the desired temperature, but stays warm for while) provides a stable temperature. Thermostatic valves allow you to divide your home into sections. Includes sanitary hot water, with no electric boiler.
• Disadvantages: it is not very efficient. The real cost of heat is high compared to other systems because it is not very efficient. It emits some greenhouse gases, although the latest heat and gas recovery technologies greatly reduce its impact. If we are in a hurry to get heat, thermal inertia can be a barrier. It does not provide cold, so it will be necessary to install air conditioning in warm areas.

Thermal heaters: very comfortable, but costly

Thermal heaters, whether they burn wood, pellets, charcoal, butane, biomass , etc., - and we include fireplaces in this classification - are an interesting option if you want to stay comfortable and cosy during harsh winters. However, they are more decorative than an efficient way of heating your home. A sub-optimal burning mechanism makes them a defective option.

• Advantages: good option in isolated places. The heat given off by these systems is very pleasant and they give the home a cosy atmosphere. In isolated places they can provide an alternative in case of a power cut. Depending on how large they are, they can be used for cooking.
• Disadvantages: inefficient. These systems are expensive and bad for the environment. Unless you install a duct system to distribute heat you will not be able to segment your home. Yet it is difficult to eliminate the thermal mass, which is why these systems are only suitable for isolated houses in places with very cold winters.

"Thermal heaters are neither efficient nor effective in many circumstances and only make sense in very specific cases."

"Thermal emitters and blue heat are only good for occasional use and in small spaces."

Saver? Comfort lover? Environmentalist? What type of user are you?

Now that you know all about the effectiveness and efficiency of the different cooling and heating options, you can choose the one that best suits your needs.

You may prefer to invest in a gas boiler and spend a little more to heat the house, but have a home that stays cosy on winter nights.

Maybe you are interested in long-term savings and, instead of investing it in the stock market, you would rather invest in future climate savings by installing an air-water aerothermal system. If you are concerned about greenhouse emissions here is how you could make your home fully electric.

Efficiency aside, each HVAC system has its advantages and drawbacks that will have a different impact depending on the individual. What may be a deal-breaker for some customers (for example: dividing up a sprawling home) will be practically irrelevant for others (those who live on a small property).

People who live on the Canary Islands need something entirely different from those living north of the Cantabrian mountain range. Other influential aspects are location and even the orientation of the house.

"Weighing up efficiency and effectiveness is a matter for each individual user, depending on their priorities and circumstances. "