The thing is, for the retrofit case (&quot;current house&quot;) it&#x27;s a different ballpark of complexity. The thing is, there&#x27;s no technical question about Ph levels - ALL houses should be built to that standard. The challenge there is political.<p>The technical challenges are in retrofit.<p>You might find Energiesprong (<a href="http:&#x2F;&#x2F;energiesprong.nl&#x2F;transitionzero&#x2F;" rel="nofollow">http:&#x2F;&#x2F;energiesprong.nl&#x2F;transitionzero&#x2F;</a>) of interest - basically factory manufactured walls with joinery, move to site, crane on.