Dagens byggeforskrifter krever mye ekstra dokumentasjon om en ikke skal ha balansert ventilasjon, og dette legger i praksis sterke føringer for valg av ventilasjonsløsning. Imidlertid er klimagassutslipp med ulike ventilasjons-konsept i liten grad undersøkt.

Global warming due to increased emissions of CO2 has lead to more focus on decreasing energy consumption and greenhouse gas emissions caused by buildings. In Norway balanced ventilation with heat recovery is the most recommended solution for a low-emission building. However, a minority claims that a naturally ventilated house can be equally sustainable.

To find out more about which concept is more sustainable, a model building with natural ventilation is compared to the same building with balanced ventilation in several cases. These are calculated in the computer-program SIMIEN, mainly with Oslo-climate. A sensitivity analysis of several parameters is also done.

The calculations indicate that the total greenhouse gas emissions in a lifetime perspective from a house with natural ventilation can be as low as from a house with balanced ventilation. A typical Norwegian passive house heated with electricity seems to have higher greenhouse gas emissions than a naturally ventilated house with 50% of the space heating covered by biofuel.

A naturally ventilated house with pre-heating of air in a earth heat exchanger, and reduced air change rate at daytime when people are out, can have equally low global warming potential as a typical passive house, when both have electric heating.

This indicates that natural ventilation, especially in a concept with wood-pellets, or district heating, can achieve very low total greenhouse gas emissions.