Calculators · Consulting

Condensation & dew-point checker

Glaser method · surface & interstitial risk

Build up the construction and set the conditions. We run the temperature and vapour-pressure profile through the wall and flag where it crosses the dew point, the first-pass screen before a full WUFI analysis.

Glaser the steady-state screening method

f_Rsi surface mould-risk factor checked

→ flags details that need full WUFI

Build-up & conditions

Element

Layers · outside → insidemm

Internal

°CRH %

External

°CRH %

Interstitial condensation · Glaser

No interstitial condensation predicted

Internal surface temperature– °C

Surface factor f_Rsi–

Internal dew point– °C

Worst-case margin– Pa

Surface stays above dew point, low mould risk

Get it checked in WUFI

A steady-state Glaser screen, not a WUFI result. It ignores moisture storage, rain, summer drying and built-in moisture. Use it to flag risk, not to clear a detail for construction.

How the screen works

Temperature falls across each layer in proportion to its thermal resistance R = d/λ.
Vapour pressure falls in proportion to each layer’s vapour resistance s_d = μ × d (a vapour control layer adds a large s_d).
At every interface we compare the vapour pressure to the saturation pressure at that temperature. Where vapour pressure would exceed saturation, condensation is predicted.
Surface mould risk uses f_Rsi = (T_si − T_e) / (T_i − T_e), checked against 0.75.

Why trust it: it follows EN ISO 13788. For anything marginal we model it transiently in WUFI, and every detail is reviewed by one of our 7 accredited Passivhaus certifiers.

Take it further

Marginal? Get it modelled transiently.

Glaser is a screen. When a detail is close, or there is a vapour-open build-up, retrofit, or built-in moisture, we run it in WUFI over a full year to see if it dries. Send us the build-up.