The green home · 01

The green apartment frame

Why the shell matters more than any sofa: insulation, triple glazing, airtightness and thermal mass are the decisions you cannot renovate in later.

Reference material, not advice for your specific build. Last reviewed September 2026.

You can repaint a wall, swap a floor and replace a kitchen. What you usually cannot change is the building itself: the thickness of the walls, the quality of the windows, the way heat moves through the structure. That is why the green home begins before the furniture arrives.

A well-framed apartment needs less heating in winter and less cooling in summer. The goal is not perfection; it is avoiding the situation where you live inside a beautiful room that is expensive to keep comfortable.

What to look for in the shell

Insulation level and where it sits — roof, exterior walls, ground floor, and especially the junctions where heat likes to escape.
Triple glazing, or high-performance double glazing with a low U-value. The extra pane cuts heat loss and almost eliminates cold drafts near the glass.
Airtightness combined with mechanical ventilation that recovers heat. A tight envelope only works if the air inside is refreshed properly.
Orientation and thermal mass. Lime concrete or similarly heavy walls absorb daytime warmth and release it at night, softening temperature swings.
A heating system that can be decarbonised later — for example, connection to a district heat network or space for a future heat pump.

Start with what you cannot replace

In a rental, you are usually choosing the building rather than changing it. In a purchase, the envelope is the part that repays attention for decades. Energy labels are useful, but they are only a snapshot; a walk-through on a cold day tells you more about drafts and cold bridges than a certificate does.

The best sustainable choice is often the one that lets you use less equipment: smaller radiators, no air-conditioning, lower bills, quieter rooms.