Nearly zero-energy buildings

The three legs

The requirement is not a single number but three conditions together:

1. Low energy demand

Good insulation, low heat loss, good airtightness, thermal-bridge-free junctions.

2. Efficient building services

Low-loss heating, domestic hot water and ventilation — with heat recovery where it is warranted.

3. Renewable energy

A significant part of the demand has to be covered from renewable sources.

If any one is missing, the requirement is not met — however good the structure is.

Where light gauge steel has the advantage

Insulation thickness grows freely

Increasing the insulation in a framed build-up does not bring a disproportionate wall thickness. For the same thermal value the whole wall can be much narrower than in traditional construction.

Airtightness is achievable

The continuous membrane layer and the service cavity are a good starting point. Service cavity.

Fast response

Because of the low thermal storage mass the building heats up quickly, which suits control.

What to watch

Thermal bridges

Because of the steel frame this is the most important item. A badly handled thermal bridge takes away the advantage in the calculation and in reality alike. Ways of breaking a thermal bridge.

Summer overheating

A well-insulated, airtight building “holds” the heat in summer too. Shading and ventilation cannot be dropped. Summer overheating.

Coordination between services and structure

The service routes go into the build-up — so coordination between disciplines has to start early.

The calculation

Compliance is demonstrated by an energy calculation, following the methodology of the decree in force. Energy performance requirements.

The point

The nearly zero-energy level does not hang on the wall but on the structure, the services and the renewables together. Light gauge steel helps most with the first leg.