Multi­family houses and service sector premises constitute 80 % of the customer stock in the Swedish district heating systems. The level of future heat use in these buildings will then have a strong influence on the future district heating economy and the cor­ responding investment demand. As a foundation for a planned study of future heat use, we have per­formed an extensive study of the current heat use for large buildings in Sweden. The input information for this study was the anonymous answers to the an­ nual enquiry of energy use in multi­family houses and service sector premises regarding 2006. Answers were available from 11253 buildings having 77.6 million square meters of residential areas and premises. By using scale factors, estimations could be made for the whole country having 310 million square meters of multi­family houses and premi­ ses. Hence, the enquiry sample constituted a large share of the whole building stock.The specific heat use was analysed by distribution, degree­days, construction year, ventila­tion system, performed conservation measures, and co­operation with other heat supply. A separate study was performed concerning high and low heat use buildings. The use of cold for cooling and water were also analysed.The results show that the individual variations are much larger than the systematic explana­tions for the parameters analysed. Just above 10% of the building spaces were high users of heat (above 200 kWh/m2). The average difference between Northern and Southern Sweden was small, implying a small climatic impact in heat use. The time period between 1965 and 1974 containing the national million dwelling program did not show dramatically higher heat use in the construction year analysis. Installed heat recovery in the ventilation gave a reduction in heat use with 11 kWh/m2 for multi­family houses. This small difference im­plies that the recovery efficiencies were only in average 20­30%. However, the heat recov­ery in service sector buildings was in average more efficient: About 50% in recovery effi­ciency. The conclusion from the conservation analysis is that the measures performed dur­ing the 10 years were done by late­comers rather than by early adopters, since the heat uses after measures in general correspond to the average level for all buildings. Out of 34000 heat pumps installed in the buil­ dings, about half of them were installed in buildings con­nected to district heating.But when more the one heat supply exists, district heat supply dominates, especially in multi­family houses.Typical users with high demands were buildings in the Västmanland and Norrbot­ ten coun­ties, fuel users, certain co­use with electricity, municipal premises, and small buildings. Typical users with low demands were buildings in the Halland county, heat pumps (but due to the systematic error of just accounting for the electricity supply to the heat pumps), state­owned buildings, and large buildings.The district heating companies can help their customers by identification of them as users with high, normal or low demands. This can be accomplished by adding infor­ mation about building space surfaces in the customer files. The heat use above the level 150 kWh/m2 was only 13 % for the multi­family houses and 14 % for the premises. Complete elimination of high use of district heat would then only give a limited, but significant reduction of the total district heat supply.

Our 6 major conclusions from the project became: • Individual variations dominate compared to systematic causes considering heatuse in multi­family and service sector buildings. • Some systematic causes were identified. • A demand exists for more local measurements of electricity used for heating, thevolume of water use for hot water. • The district heating companies can help their customers to identify them as high,medium or low users of heat. • On short term, a significant potential exists for lower heat use in the Swedishmulti­family and service sector buildings. • More efficient heat use in building will probably be the most important competi­tor to district heat supply in the future.

This thesis concerns the development of a measurement method for determination in the field of the thermal conductivity of the insulation in buried district heating mains.

The thermal conductivity of the insulation is calculated from the measured value of the radial heat flow through the heating main, the measured temperature difference across the insulation, and the dimensions of the heating main. The heat flow has been measured with a heat flux sensor which was fitted to the surface of the casing. The temperature has been measured with copper/constantan thermocouples.

It is a necessary condition for the method used in the project for determination of the thermal conductivity of the heating main insulation that the heating main is uncovered and is not in contact with the surrounding soil over a distance of about 1.5 m and that the measurements are made directly on the heating main. In this way, no account need be taken of the material surrounding the heating main, nor of the effect of this material on the measurements. No interference is needed with the heating main which would affect the distribution of the district heating water, and the heating main can remain in operation during measurements.

Shielding insulation consisting of preformed insulation sections which were placed over the casing of the heating main and covered the heat flux sensor and some of the casing. The function of this insulation was to shield the heat flux sensor from external thermal disturbances. In the field measurements, a copper guard plate of 0.5 mm thickness, the temperature of which could be adjusted, was also placed over the shielding insulation in order to maintain the temperature on the heat flux sensor as constant as possible.

When temperature and heat flow are measured, the instruments used will be affected by conditions which prevail at the time of measurement. It is therefore very important to analyse the sources of error which may arise in the measuring situation at hand.

The effect of these factors on the measured values has been studied by

' laboratory measurements

' theoretical calculations

' field measurements

On the basis of the resulting values of heat flows and temperatures obtained in field measurements on plastic heating mains which were operating under normal conditions, the thermal conductivity of the insulation of the main has been estimated.

The method has been tested on plastic heating mains with directly foamed insulation, since this is the most common type of heating main both in the existing district heating network and in new construction. The measuring method can also be used on other circular heating mains.

This study focuses on the necessity of having knowledge about different energy saving measures when renovations and reconstructions are planned and designed. It is also of great importance to have routines to follow up what effects the actions taken have had on the energy consumption as well as on the indoor climate when the renovation is completed. A big part of the existing buildings in Sweden are built during a ten-year period between 1965 and 1974. When these buildings are to be renovated there is a great potential for energy saving.

This study focuses on the importance to reduce the energy consumption when buildings are reconstructed, in order to decrease the environmental impacts. When reconstructing/renovating buildings it is important that the actions taken result in buildings with both low energy consumption and a good indoor climate. It is also important that all parts involved in the building process are aware of the close relationship between the use of energy in buildings and the indoor climate. This paper describes the actions taken in order to save energy when some buildings built between 1966 and 1970 in Halmstad, Sweden, were renovated/reconstructed, and how these actions have influenced the indoor climate. © Copyright 2013 Elsevier B.V., All rights reserved.

In the IEA Network Supervision project a special method, the Tx-factor method, is investigated. Several other methods exist for in-situ heat loss determination from district heating (DH) pipes. These methods have advantages and disadvantages compared to the Tx-factor method. It is the purpose of this work to make a comparison of the methods on a particular DH pipe. This makes this investigation special as in most previous work only one or very few methods have been applied on the same DH pipe. The purpose of this work was thus to go out to the site and make measurements of the heat loss from the DH pipe at this particular time of the year - an estimate of annual heat losses could then to be made afterwards. The aim of this work being to develop methods for practical applications not very sophisticated tools were used at the experimental site. This means that although very advanced equipment could have been used for determining the centre line and the depth of the DH pipe only measurement sticks, water levels and strings were used. For the same reasons the temperature sensors were installed by using measurement sticks

This report presents some measurements for determining thermal conductivity in different materials, using a single thermistor. This thermal conductivity measurement technique is appropriate for materials like fine-grained soils, gel-like materials such as silicon grease, and insulation materials. To verify the usefulness of this method, additional measurements are needed for several materials with well-known thermal conductivities, especially solid materials with thermal conductivity in the range of 0.5-2.5 W/m C.

The current heat use refers normally to the average heat use in a country or a sector during the course of a year. But it is also important to be aware of the distribution of high to low use when estimating the potential for reducing total heat use.Energy statistical data published in the annual report from Statistics Sweden have been supplemented by a deeper analysis of distribution of heat use and systematic causes regarding high heat use.The aim of this paper is to explain the variation in heat use with respect to construction year, degree days and energy efficiency measures.In the Swedish energy efficiency debate, many voices refer to systematic causes for high heat use. However, the results from this study do not support this opinion, since the use distribution mostly comes from individual causes. The most important implication of the study results is that systematic policy measures will have a low impact on the total national energy efficiency.