Quite expensive? That's understated. My understanding now is that it comes at the cost a modest new house.

Our family bought a house in the immediate periphery of a smaller city. Since most city housing here is old, the consequence of that decision is that our modest city home has abysmal energy efficiency.

I have wanted to renovate ever since we bought it, in order to cut down on our carbon footprint before 2030, but I have given up on the idea that we'll be able to afford a heat pump before then.

After having spoken with several architects, the building cost alone will eat up €200K without any frills. This will make our house smaller, by replacing poorly built annexes with a more compact and thus thermally efficient cube shaped annex. This comes on top of the mortgage that we took out.

So ironically, in making our home more energy efficient, we would also be making it smaller and less desirable in this regard, at a great expense. Tacking on a heat pump and PV panels would inflate the cost by another 10%.

That is the very real cost of making a home suitable for low energy heating systems.

Don't get me wrong, I'm counting my lucky stars that I'm able to consider such an undertaking, but going through this exercise myself is just a reality check of how dire the situation really is.

If we want to achieve net zero in housing, can we really do so at the cost of conventional building practices?

Talking about the local situation, less than a third of homes are from after 1981 [1]. That's millions of homes slated for a similarly-priced revamp. Who is going to foot the bill? Even with government incentives, some owners don't want to spend all that money on something as intangible as low energy housing, and others simply can't afford to.

[1] https://statbel.fgov.be/en/themes/housing/building-stock