The precision of methods used for the determination of hygric properties of porous building materials was investigated. The study was performed in the framework of the EU-initiated HAMSTAD-project. Six laboratories measured the selected hygric properties of three porous building materials. While the most measured properties show acceptable agreement, yet, it was found that some of the existing standards or commonly accepted measurement methods need improvement. Most striking were large variations in the results of the vapour transmission tests performed in accordance to the existing European Standard.

The standardised Glaser method for calculation, prediction and evaluation of moisture performance is considered as rarely applicable. The present state of knowledge, analytical as well as experimental, concerning heat, air and moisture demands updating of standards. This paper presents five numerical benchmark cases for the quality assessment of simulation models for one-dimensional heat, air and moisture (HAM) transfer. In one case, the analytical solution is known and excellent agreement between several solutions from different universities and institutes is obtained. In the remaining four cases, consensus solutions have been found, with good agreement between different HAM models. The work presented here is an outcome of the EU-initiated project for standardisation of HAM calculation methods (HAMSTAD WP2).

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The Boltzmann transformation method is used to determine the liquid water diffusivity from moisture content profiles as measured in a capillary water absorption experiment. An inter-laboratory comparison for analyzing the reliability of the determination method showed that the inaccuracy in the liquid water diffusivity is caused by scatter in the transformed data and by uncertainty in the boundary conditions at the intake surface and ahead of the steep moisture front. A methodology is proposed based on (1) the evaluation of the validity of the diffusion approach, (2) a simplified handling of the boundary conditions, (3) smoothing of the scattered data and (4) the evaluation of the quality of the determined liquid water diffusivity. For HAM (Heat-Air-Moisture transport) calculations values of the liquid water diffusivity for moisture contents higher than the capillary moisture content are disregarded. The liquid water diffusivity can be described by an exponential function limited at a lower moisture content bound.To describe the moisture diffusivity including liquid water and water vapour transports, a new parametric description of the moisture diffusivity is presented, which shows sufficient flexibility both in the hygroscopic and overhygroscopic ranges. When permeability is calculated from diffusivity, the permeability should monotonically increase with decreasing capillary pressure. In the hygroscopic region it should coincide with the measured water vapour permeabilities.

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A comprehensive modular behavioural model for office buildings and its coupling to building simulation software is introduced, developed to be used in energy uncertainty analysis in a straightforward manner. The model includes the inherent variability in behaviour amongst individuals by defining representative active and passive users. The ratio of the latter serves as an input for the uncertainty analysis. The behavioural model consists of submodels for occupancy, use of shading system, window operation, control of artificial lighting, heat gains by appliances and the control of heating and cooling set points. All these submodels are selected from a literature review. The review revealed a lack of validation and intercomparison of the models as the principal weakness of the research field. The methodology is applied in a Monte Carlo analysis of the uncertainty on the simulated energy demands of an office building at the building level, yielding moderate uncertainties.

When comparing calculated heating consumption in residential buildings assuming standard usage with standardized measured data, then the two typically does not fit. In fact, measured consumption may be a fraction only of what was calculated. The reason is direct rebound behavior by the inhabitants. The paper shows the importance of direct rebound through measured results. First the temperatures, recorded in daytime and sleeping rooms in a sample of dwellings, are commented. Then follows a discussion of the indoor temperatures found when calculated energy consumptions for heating were forced to give the same numbers as measured. Next, two small scale analyses of energy data gained in low-income estates are commented, followed by test results on direct rebound in two dwellings, one non-insulated, the other well insulated. These data prove that the benefits of direct rebound are much larger in non-insulated than in well insulated homes. That fact is used to construct a rebound curve, starting from the normalized consumption data gained in 964 houses. The paper ends by showing the effect of energy price on direct rebound.