Abstract
Aresidential building, constructed with an unvented attic, is acommonroof assembly in the United States.The expected hygrothermal
performance and service life of the roof are difficult to estimate due to a number of varying parameters.Typical parameters
expected to vary are the climate, direction, and slope of the roof as well as the radiation properties of the surface material. Furthermore,
influential parameters are indoor moisture excess, air leakages through the attic floor, and leakages from air-handling unit
and ventilation ducts. In addition, the type of building materials such as the insulation material and closed or open cell spray
polyurethane foam will influence the future performance of the roof.
A development of a simulation model of the roof assembly will enable a risk and sensitivity analysis, in which the most important
varying parameters on the hygrothermal performance can be determined. The model is designed to perform probabilistic
simulations using mathematical and hygrothermal calculation tools. The varying input parameters can be chosen from existing
measurements, simulations, or standards. An analysis is applied to determine the risk of consequences, such as mold growth, rot,
or energy demand of the HVAC unit. Furthermore, the future performance of the roof can be simulated in different climates to
facilitate the design of an efficient and reliable roof construction with the most suitable technical solution and to determine the
most appropriate building materials for a given climate