What are passive houses? Comfort for the home and the environment

Sustainability has gone from being the future we were looking to some time ago to a real and latent present for which we must all work at all levels and in all sectors. The last Climate Summit, held in Glasgow, set a new target: to reduce global emissions by 30% by 2030.

A proposal by US President Joe Biden, which the EU has supported, as have other world leaders. It is therefore urgent to take action, and from the construction sector we must and can contribute to this goal, especially because we have a housing stock in Spain that is on average more than 40 years old. Above all, because we have a housing stock in Spain that is on average more than 40 years old. What does this mean? It means that our houses do not comply with current energy efficiency regulations and have become the great energy predators of cities, responsible for 40% of the emissions released into the atmosphere.

Because the age of the houses definitely influences how they are built and under what parameters. And in these 40 years things have changed a lot. Because we now have data on how much energy homes demand and also how much they lose due to inefficient construction. That is, without proper thermal insulation.

Because these systems, which wrap the façade on the outside as a shelter, can reduce energy losses in houses by up to 30%, both in summer and winter, keeping them always at a comfortable temperature and avoiding the abuse of thermostats and excessive energy consumption indoors to keep warm in winter and cool in summer.

A solution that is essential to reduce the energy and environmental bills that homes are currently costing us. In a context, moreover, of an unprecedented increase in the cost of electricity bills. That is why it is time to take a step forward and talk about a new housing concept, the ‘passive houses’.

What are passive houses?

This is the ‘Passivhaus’, a concept of German origin that is becoming increasingly popular in Spain, especially in Navarre, one of the regions with the most certified projects. These buildings require only 10% of the energy used by an average home, as their construction standard combines a high level of indoor comfort with very low energy consumption.

This is achieved by taking maximum care of the thermal envelope, i.e. the insulation of the home, eliminating thermal bridges through which energy escapes. In addition, they have a high degree of air tightness and a mechanical ventilation system with heat recovery, and the little energy they require can be obtained from renewable sources.

We are therefore talking about environmentally friendly construction with a huge demand on resources. In fact, the figures speak for themselves. In Spain, with the first 75,000 square metres of Passivhaus built surface area, according to the Passivhaus Building Platform (PEP), in just six years they stopped consuming 1,845,892 KWh of final energy, i.e. a saving of almost 280,000 euros in energy bills. In addition, the first 90 passive houses already built in Spain have stopped emitting CO2 equivalent to that absorbed by 51,266 trees.

Systems on which passive houses are built

At Molins we have our Propam Aisterm external thermal insulation system (SATE), which is essential for energy saving and for the construction and certification of passive houses, as it eliminates the appearance of thermal bridges, minimises the risk of condensation and does not contribute to overloading the structures, due to the fact that it does not use pieces of high weight and size.

And all this at a lower economic cost than other solutions with similar thermal performance. The future is already well underway and this type of building is where we should be heading. Moreover, with solutions that also do as little damage as possible to the planet, something that is the focus of our daily work at Molins: designing sustainable solutions and products for an increasingly sustainable construction.