English

The average UK household spends about +500 per year on heating, lighting and power for domestic appliances but there is a huge variation between individual household expenditures. Field trials, in which the energy use in occupied dwellings is measured, show that the physical characteristics of the dwelling and the lifestyles of the occupants are about equally important in determining energy consumption. It is clear, therefore, that realistic estimates of domestic energy consumption can only be made if both these factors are considered together.

Three thermal analysis methods with different degrees of empiricism are quantitatively investigated regarding the ease of use, efficiency, accuracy and redundancy of generated information. From this investigation it is concluded that, for design purposes, a sensitive interplay between experiment and theory can often lead to an optimum method. 

This paper extends an earlier investigation of scale effects on buoyancy driven recirculating flows in stairwells of the kind adopted in domestic accommodation. Further consideration is given to the role of Reynolds number, which proves to have unexpected features, possibly because stairwell flows fall into the range of incipient instability. A technique is developed to introduce explicitly the fraction defining the way in which the energy loss from the system is divided between the regions above and below the stairway.

The article in last month's issue of "Energy Management" gave a brief overview of the Energy Efficiency Office's programme of demonstrations in the housing sector, as managed by BRE the Building Research Establishment. In the case of new housing, these are showing the benefits of integrating packages of energy efficiency measures into the designs of range of dwelling types.

 It was generally recognised that because of occupants' behaviour, natural ventilation rates were usually much lower than the accepted criteria for calculation. A great deal of anecdotal data existed which showed that frequency of opening windows bore a direct relation to external temperature and that the greater the volume the less the frequency of opening. The recent BRE survey also shows that very low ventilation rates, below 4 cubic metres/ person/hr have been found to be acceptable.

The report gives the first results of the measurement campaign of 1986-1987. The 'Lindeman' housing estate was built by the coal mine of Zolder for its miners shortly after the 2nd World War (1947-1948). The estate consists of about 230 dwellings and accommodates 272 households. The majority of the population consists of immigrants, especially Turks and Italians, people who are used to another, hotter climate than the wet cold temperature climate in Belgium. The rented houses were refitted in 1981.

Two methods for reducing weather data are assessed and compared with respect to use for heating calculations. Degree days for calendar months, utility bill periods and without weekends were calculated and compared along with temperature 'bins' of various sizes using the CIBSE Example Weather Year. Wind velocity and solar radiation are also analysed with respect to degree days. Both methods, degree days and the bin method, are found to represent the actual weather conditions adequately for use in heating calculations.

This paper summarises the work of the CIBSE Example Year Task Group. Its main task has been to develop a methodology for the selection of representative weather data. This data is required as input to the various procedures available for the estimation of the energy performance of buildings and their engineering systems. As a further aid to applying a consistent set of meteorological data as input to energy calculations, the Task Group's work has extended to the preparation of a set of algorithms for calculating psychrometric properties 

In building design the ability to predict the effects of daylight is of increasing importance. Daylight can be an important factor in building energy efficiency; in some buildings lighting may account for half the energy cost. This paper describes the weather data that are available for daylight prediction.  First of all the requirements for data are evaluated. For many energy applications, the key quantity is the percentage of the working year a given design illuminance is exceeded by daylight.

The objective of this paper is to present validated mathematical models for estimation of hourly and daily solar irradiation on surfaces of arbitrary orientation and tilt from irradiation on a horizontal plane. Daily irradiation on a surface may still be estimated even if only the hours of sunshine are known. To do this regression equations have been established to estimate the hourly or daily diffuse irradiation, given the corresponding horizontal global irradiation.