An experiment was conducted to concentrate on the rainfall interception process of individual trees for four common species in Beijing, China, which included needle species (Platycladus orientalis and Pinus tabulaeformis) and broadleaf... more
An experiment was conducted to concentrate on the rainfall interception process of individual trees for four common species in Beijing, China, which included needle species (Platycladus orientalis and Pinus tabulaeformis) and broadleaf species (Quercus variabilis and Acer truncatum). Two types of interception storages, the maximum (Cmax) and the minimum interception storage (Cmin), were examined at four simulated rainfall intensities (from 11.7 to 78.5 mm h−1). Results showed that an average of 91% of Cmax for all the species was intercepted during the first 10 minutes of rainfall, while 45% of Cmax drained off after rainfall cessation. Leaf area index (LAI) and leaf area (LA) were significantly correlated (p < 0.05) with Cmax and Cmin, while such significant correlations were not found between rainfall intensity and Cmax and Cmin. Average Cmax and Cmin across all the species corresponded to 3 and 1% of gross rainfall. Mean Cmax and Cmin of the needle species were 3.0 and 1.8 tim...
As regulations regarding energy use and emissions of CO2 equivalents in buildings become more stringent, the need for more accurate tools and improved methods for predicting these parameters in building performance simulations increases.... more
As regulations regarding energy use and emissions of CO2 equivalents in buildings become more stringent, the need for more accurate tools and improved methods for predicting these parameters in building performance simulations increases. In the first part of this project, a probabilistic method was developed and applied to the transient energy calculations and evaluated using a single-family dwelling case study. The method was used to successfully predict the variation of the energy use in 26 houses built in the same residential area and with identical building characteristics and services. This project continues the development and testing of the probabilistic method for energy calculations by applying it to a multi-family building. The complexity of the building model increases as the multi-family model consists of 52 zones, compared to the single-zone model used for the single-family dwelling. The multi-family model also includes additional parameters that are evaluated, such as ...
A vertical temperature stratification normally exists in rooms during the heating season in cold climates. An expression of the gradient in apartments heated by hydronic radiator heating systems with exhaust ventilation has earlier been... more
A vertical temperature stratification normally exists in rooms during the heating season in cold climates. An expression of the gradient in apartments heated by hydronic radiator heating systems with exhaust ventilation has earlier been developed assuming a dependency of the outdoor temperature. The expression was used by a public real estate owner when re-calculating measured indoor temperature at 2.1 m above floor to 1.2 m above floor representing the occupancy zone and used for individual metering and billing of space heating cost. To validate the suggested expression temperature measurements have been made at four heights in living rooms in apartments built in the 70’s. The heights includes 0.0, 0.1, 1.1 and 1.7 m above floor. The theoretical expression has been compared to the full-scale measurements and in general the expression overestimates the vertical temperature gradient. The measured gradients are generally very low. The thermal comfort in the aspect of vertical temperat...
ABSTRACTBetween the years of 1965 and 1975 some one million apartments were built on an industrial scale in Sweden. The intent was to provide the quickly growing population with modern housing featuring reasonably sized apartments and... more
ABSTRACTBetween the years of 1965 and 1975 some one million apartments were built on an industrial scale in Sweden. The intent was to provide the quickly growing population with modern housing featuring reasonably sized apartments and good functionality; such as central heating and modern kitchens and bathrooms.Some forty years later many of these large multi-family dwellings are in dire need of substantial renovation and improvements to extend their life expectancy and improve their desirability.Improved energy performance is under the current circumstances a demand from both the national government, EU and the property owners. Previous historical experiences from trying to reduce energy use in buildings has made concerned parties aware that care must be taken to, among other things, avoid reductions in indoor air quality and minimizing the risk of moisture damage in structures. This paper is an overview of some common features of these Swedish multi-family dwellings and some of th...
The use of hygrothermal calculation tools for dimensional purposes in the design phase is common. However, used tools are usually not blindly verified in real, on-site conditions. This paper present a method for verification of... more
The use of hygrothermal calculation tools for dimensional purposes in the design phase is common. However, used tools are usually not blindly verified in real, on-site conditions. This paper present a method for verification of hygrothermal calculation tools for real-life, situations. In the method calculations become carried out before the measurement results are known, i.e. by blind calculations, which afterwards are compared with measurements. The main conclusion is that blind validations are reliable since intentional or unintentional adjustments of calculated results, to obtain better correlations to the measured values, are impossible. Other positive effect is that information about how the user perceives the tool could be found since the blind calculations are similar to the designer situation in daily work. (Less)
Calculation of relative humidity and temperature in an early stage of the design process is important to avoid moisture damages in wooden walls. Previous studies show that a sufficient air flow in the air gap behind the facade panel is... more
Calculation of relative humidity and temperature in an early stage of the design process is important to avoid moisture damages in wooden walls. Previous studies show that a sufficient air flow in the air gap behind the facade panel is important to ensure a moisture safe construction. This study investigates if blind WUFI 5.0 calculations with a varied air flow in the air gap behind the facade give a better correlation to measured values compared to calculations with a constant air flow. Calculations for two cases are compared to measured values in single family house. The results show that calculations with a wind dependent air flow does not necessary give better correlation to measured values compared to calculations with a constant air flow. However, the calculated values are confirmed with measured values during the warm period and there are deviations in the outer part of the wall during the cold period. Variations in measured values at the same depth in different places in the...
Stricter Swedish building regulations require a moisture-safety design process to be carried out before houses are built. In order to predict moisture-critical conditions, a properly verified, user-friendly and reliable calculation tool... more
Stricter Swedish building regulations require a moisture-safety design process to be carried out before houses are built. In order to predict moisture-critical conditions, a properly verified, user-friendly and reliable calculation tool that could be used in this design phase, is required. This paper initially presents a blind method that could be used in order to verify heat and moisture calculation tools in a reliable manner. Furthermore, general results and findings from blind validations using a transient heat and moisture calculation tool are summarized and presented.The comparisons include measurements and calculations of temperature and relative humidity and were carried out in northern European climates. In general, the results show a good correlation between measured and blindly-calculated values. Comparisons show that the studied tool can be used during the design phase to predict moisture risks. However, factors such as the influence of impaired-temperature measurements o...
