Development of a statistical model to assess the climate conditions in the ventilation layer of double pitched roofs

Johannes Tieben,Julia Bachinger,Bernd Nusser,J Kurnitski,T Kalamees

doi:10.1051/e3sconf/202017211005

Abstract

For the proper simulation of hygrothermal processes in roof constructions with ventilation layers the knowledge of climate conditions within the ventilation layer is requisite. In this work a model for the assessment of temperature and air humidity has been developed using multiple regression analysis. Therefore, the climate conditions inside the ventilation layers of differently covered and oriented roofs have been monitored for one year. Relevant outside climate parameters for the calculation of ventilation layer climates have been identified. The comparison between measured and calculated values indicated an adequate accuracy of the developed model with limitations for the use in snow fall periods.

Highlights

In recent years the hygrothermal simulation became a standard process to evaluate different roof constructions for its moisture protection performance
A proper simulation is already well established as the outdoor climate with its hourly parameters for temperature, air humidity and global radiation is directly available at different sources for numerous sites (e.g. Meteonorm Software [2], WUFI software climate databank [3])
Considering only the outside temperature (Te) into the model is insufficient to assess the temperature inside the ventilation layer (Tvl)

Summary

Introduction

In recent years the hygrothermal simulation became a standard process to evaluate different roof constructions for its moisture protection performance The basis for these simulations is a defined indoor climate as well as a site-specific outdoor climate to calculate the heat and moisture transfer through the construction between the outside and inside. Heat transfer processes through the roof covering to the inside of the ventilation layer have a strong influence on temperature within the ventilation layer and on referring air humidity in this area. These processes strongly depend on solar absorption and long wave emission behaviour as well as on the heat capacity of the roof covering. The forced convection through wind as well as the thermal buoyancy is affected in case of changing orientation and slope of the roof

Methods

Results

Conclusion