Energy efficiency – facts and figures

Making your house more efficient is good for the environment, but also for your wallet

We all know the importance of a good insulation in order to reduce energy dissipation and save money. But how much energy do we use for heating, and most of all how much energy can we save with a few improvements? In other words, should carbon emissions be reduced just for ethical and environmental reasons, or is there a real economic benefit?

Let’s consider a few figures. A building dating back from the 1980s, usually characterised by a low energy efficiency, requires between 150 and 250 kWh/m² per year in temperate climates. Assuming an average consumption of 180 kWh/m² and a flat measuring 140 m², we get a total energy consumption of 25.200 kWh per year: an incredibly high value.

This home would cost about 1285 Euros if heated with a wood pellet stove, 1915 Euros if heated with a methane-fired boiler, 3250 Euros if heated with a diesel oil-fired boiler, and 4230 Euros if heated with a LPG-fired boiler with a private tank. With the irreversible increase of fossil fuels prices one can imagine how this expense will increase year after year.

An efficient insulation can noticeably increase overall efficiency, lowering energy demand down to 30 kWh/m² or even less (KlimaHaus Class “A”), which corresponds to an heating bill about 6 times lower, that is a 80% saving. For the aforementioned fuels it means an expense of 215 Euros for wood pellets, 320 Euros for methane, 540 Euros for diesel oil and 700 Euros for LPG. Savings range from 1070 and 3530 Euros per year.

What are the improvements to be carried out to better insulate one’s house? External thermal insulation coating, roof insulation and efficient boilers are surely useful. However, if we consider that more than 50% of heat is lost through the windows, we see that the first and most important thing is window renovation. An eco-friendly and efficient double glazed window, with a low-emission glass, allows for a fast amortization also thanks to tax allowances. Quality windows should be optimized according to the building on which they will be installed. When properly installed they represent a real investment that will pay itself back in a few years, while increasing the overall value of the building.