Torben Valdbjørn Rasmussen

Retrofitting Listed Buildings: Measures, Savings and Requirements

The paper presents a case study where the energy demand for a listed building constructed in 1900 is reduced. Many older buildings are listed and have restrictions that include the entire building or that include only its exterior. For the building presented, only its exterior facade is listed. The paper demonstrates measures for the improvement of the thermal insulation of the building with solid brick walls. Durable customised measures are shown. The customised measures are required not to change the overall exterior architecture as the building is considered to contribute to the uniqueness of the local urban environment and therefore listed. The reduced energy demand, related to individual measures, is estimated and building physics requirements are addressed together with the economic options for evaluating the profitability. Tightened requirements to the thermal insulation of new buildings and the resulting demand for a reduction of the energy consumption for heating and comfort, in order to re- duce CO2 emissions, mean that existing and especially older buildings are categorised as having a very low thermal stan- dard compared with todays requirements. Therefore, there is an increased interest in improving the thermal insulation standard of many existing and older buildings. However, many older buildings have restrictions that protect the entire building or that protect only its exterior. Therefore custom- ised solutions reducing the energy consumption are needed for these buildings. Moreover, close attention should focus on preventing degradation of the existing construction when the energy needed for heating and thermal comfort of a building decreases, as a result of measures to improve the thermal insulation. Besides lower heating costs and reduced CO2 emissions, the improvements of the standard of insula- tion could contribute to the elimination of other aspects of discomfort. The aim of the paper is to show solutions that improve the thermal insulation standard of a building with a listed exterior facade. The paper includes technical solutions for improving the thermal insulation standard by showing cus- tomised thermal insulation measures of the building enve- lope. It also addresses issues that must be considered in order to prevent moisture-related degradation of the original build- ing. Furthermore, a simple and accurate method for estimat- ing the decreased energy demand after improvements is ap- plied. Finally, the profitability of the measures is evaluated. The paper is based on guidelines on how to improve the thermal insulation of existing buildings and blocks of flats published by the Danish Building Research Institute (1).

A Control Theoretical Approach to Active Vision

Integration of active vision processes is a primary problem for construction of systems that have a robust performance. Active vision systems may be broken up into fixation, pursuit, and attention processes. These processes have very different spatio-temporal scope. If the scope is used as a guiding principle for organizing a system, a hierarchical architecture can easily be formulated. The integration strategy can in addition be based on traditional control methods, where different error/position estimates are integrated using simple summation between the control loops. In this paper we have demonstrated how image based processes, 2D and 3D tracking processes may be integrated into a coherent system. A system that is based on these principles has been designed and implemented. The system can operate at a speed of 7 Hz is fairly general settings. Experiments with the implemented system has shown that the performance of such a system is superior to the traditional 2D tracking systems.

Variation in residential radon levels in new Danish homes.

Radon-222 gas arises from the radioactive decay of radium-226 and has a half-life of 3.8 days. This gas percolates up through soil into buildings, and if it is not evacuated, there can be much higher exposure levels indoors than outdoors, which is where human exposure occurs. Radon exposure is classified as a human carcinogen, and new Danish homes must be constructed to ensure indoor radon levels below 100 Bq/m(3). Our purpose was to assess how well 200 newly constructed single detached homes perform according to building regulations pertaining to radon and identify the association between indoor radon in these homes and municipality, home age, floor area, floor level, basement, and outer wall and roof construction. Median (5-95 percentile) indoor radon levels were 36.8 (9.0-118) Bq/m(3) , but indoor radon exceeded 100 Bq/m(3) in 14 of these new homes. The investigated variables explained nine percent of the variation in indoor radon levels, and although associations were positive, none of these were statistically significant. In this study, radon levels were generally low, but we found that 14 (7%) of the 200 new homes had indoor radon levels over 100 Bq/m(3). More work is needed to determine the determinants of indoor radon.

Verification of Density Predicted for Prevention of Settling of Loose-fill Cellulose Insulation in Walls

This paper discusses the verification of the density predicted for prevention of settling of loose-fill cellulose insulation in walls when criteria for creep in granular materials are applied. The practical use of an earlier presented theoretical framework and an experimental verification are described. The empirical framework allows a quantitative approach to the problem of achieving non-settling of a loose-fill insulation material in a given wall. The prediction involves the use of three experimentally determined parameters that govern the density of a loose-fill insulation material required to ensure volume stability in a wall exposed to climates. One parameter is determined from tests on a wall exposed to constant humidity conditions and two parameters are determined from tests on walls exposed to time variable humidity conditions. A theoretical description of creep is used that describes the parameter for walls exposed to constant environmental conditions. The parameters for an extended empirical model for predicting creep of material exposed to alternating humidity are determined from the corresponding tests. The uses of the parameters are shown together with associated characteristics for one loose-fill cellulose insulation material under one set of exposures. Full-scale wall tests in one wall cavity configuration under the same set of exposures showed that the method did predict results that are in the right magnitude. In addition it is shown that for many cycles with in-time variable humidity conditions, creep of the loose-fill cellulose insulation material almost reached equilibrium.

Prediction of Density for Prevention of Settling of Hygroscopic and Nonhygroscopic Loose-fill Insulation in Walls

This paper discusses the prediction of the density necessary for the prevention of the settling of hygroscopic and nonhygroscopic loose-fill insulation in walls, when the criteria for creep in granular materials are applied. The practical use of a theoretical framework presented earlier and the material characteristics used to develop an equation from which the necessary density can be predicted, are described. The empirical framework allows a quantitative approach to the problem of achieving nonsettling of a loose-fill insulation material in a given wall. The study involves the use of empirically derived equations to predict the density of a loose-fill insulation material required to ensure volume stability in a wall exposed to one type of cyclical humidity conditions. An empirical model for predicting the creep of materials has been developed in earlier papers. The creep was determined from the corresponding tests. The use of the method is demonstrated by showing the results from a full-scale wall test. The method is applied for different cavity sizes together with the associated characteristics of four hygroscopic and one nonhygroscopic loose-fill insulation materials exposed to the same climatic conditions. In addition, it is shown that for many repeated cyclical humidity conditions, the creep of the hygroscopic and nonhygroscopic loose-fill insulation materials asymptotically approached equilibrium.

Refurbishing Fæstningens Materialgård: A Heritage Complex

Faestningens Materialgard is a listed complex located in downtown Copenhagen. The refurbishment of the listed complex was studied to provide knowledge on how a process for refurbishing heritage buildings can be carried out successfully, as refurbishment of heritage buildings is often a complicated process. The process shows how to choose, evaluate and implement measures creating synergy between the interests of preserving heritage values and to develop affordable refurbishment that meets the requirements for the future use of the building. The refurbishment followed included restoration, energy upgrading and refurbishment of the individual buildings that make up the listed complex. The process focuses on the cooperation and dialogue between the parties involved. Faestningens Materialgard is a case study where the Heritage Agency, the Danish Working Environment Authority and the owner as a team cooperated in identifying feasible refurbishment measures. Through the process the owner was supported by architects and engineers. Focus is put on how, to identify potential energy savings and, to decide on energy upgrading measures when refurbishing and restoring listed buildings. The refurbished Faestningens Materialgard is visualized in photos.

Integrated Strip Foundation Systems for Small Residential Buildings

A prefabricated lightweight element was designed for a strip foundation that was used on site as the bases of two small residential buildings, in this case single-family houses; one was built with a double-brick exterior wall separated by mineral fiber insulation and the other was built with a wood-stud exterior wall with mineral fiber insulation. The element was placed on a stable surface underneath the top soil layer, just 0.25 m below the finished ground surface. The prefabricated element was designed to comply with the requirements of a high energy-efficient performance stipulated in the new Danish Building Regulations. The base of the two individual buildings was cast in one working operation and completed within two working days. Produced and shaped as one coherent element of expanded polystyrene, the element was designed to be handled on site by one man. Non-freezing ground was established by using outer insulation located at the outer plinth. Temperatures were measured at measurement points at the outer plinth and onwards from these points beneath the building. In addition the soil temperature, the temperature within the concrete floor slab and outdoor as well as indoor temperatures were measured.

Novel Radon Sub-Slab Suctioning System

A new principle for radon protection is currently presented which makes use of a system of horizontal pressur- ised air ducts located within the lower part of the rigid insulation layer of the ground-floor slab. The function of this sys- tem is based on the principles of pressure reduction within the zone below the ground-floor construction. For this purpose a new system of prefabricated lightweight elements is introduced. The effectiveness of the system is demonstrated for the case of a ground-floor reinforced concrete slab situated on top of a rigid insulation layer (consisting of a thermal insula- tion layer located on top of a capillary-breaking layer) mounted in turn on stable ground. The new system of prefabricated lightweight elements consists of the capillary-breaking layer and a pressure-reduction zone which is working as the radon- suction zone. The radon-suctioning layer is formed from a grid of horizontal air ducts with low pressure which are able to remove air and radon from the ground. Results showed the system to be effective in preventing radon infiltrating from the ground through the ground-floor slab, avoiding high concentrations of radon being accumulated inside houses. For the system to be effective, the pressure within the ducts must be lower than the pressure inside the house. The new principle was shown to be effective in preventing radon from polluting the indoor air by introducing low pressure in the horizontal grid of air ducts. A lower pressure than the pressure inside the building must be established. The prefabricated lightweight elements were integrated into the insulation layer below the material of the ground-floor slab. The element and the insula- tion material were made of expanded polystyrene. The new element can be handled by one man on site.