qualitative assessments have been made as these would be based on the authors’ subjective viewpoint. Where quantitative data have been used the source is clearly identified. The objective was not to say what is good or bad about the intelligent systems, but the variations of incorporating the technologies into buildings. Readers are left to form their own opinions on the basis of the material presented. It was not possible, or even appropriate, to enter into a full-scale monitoring and analysis programme at this stage. A more in-depth academic study would clearly warrant a greater emphasis and the finances to support such an effort. Where monitoring results are already available for projects (79%), their principal findings have been incorporated.
The purpose of this study is to present in a single document, the range of intelligent façades employed in built projects from across the world.
Each case study begins with a descriptive section detailing the name of the project, the building type and the location. As well as crediting the architect, the energy consultant and client are also credited as important contributors.
The dates are given from the project’s inception and completion. The degree of latitude was calculated as an indicator of climate and solar geometry. The primary axis of the building’s orientation is given relative to north.
The buildings are also credited with a range of intelligent features which are characteristic of intelligent systems, including a building management system with learning capabilities; if weather data are collected; whether lighting circuits are responsive to daylight levels or occupancy; if there are any
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The case studies
8
sun-tracking facilities; whether occupants are able to override façade func-tions; self-generation systems such as CHP, PVs, and wind; whether automatic night cooling is used; and if solar water heating is employed.
The introductory section for each building describes the background to the project, and describes the key intelligent characteristics as an ‘intelligence factor’
– the qualifying criteria. Details of the client’s briefing and programme require-ments are followed by a short description of the building, the distribution of functions, the accommodating form and details of occupancy. A summary of the energy strategy describes the method used to limit energy consumption in the project. Details of the site and limited climatic data are provided to set the building in its physical and climatic context. A sunpath programme has been used to depict the sunpath for each case study building. The sun’s path is shown in a continuous line for the winter extents (21 December) and in a dashed line for the summer extents (21 June). The summer and winter solar elevations at midday are also given as an indication of the peak solar altitudes.
The general description of the buildings includes details of the construction in terms of materials used and insulation thicknesses. U-values are given in W/m2K as a quantitative measure of thermal transmission. An assessment is made by the authors of the quantity of glazing on each face of the building, including the roof, by calculating the façade transparency as a percentage.
Where full-height glazing is employed transparency is assumed at 100% with no allowance for opaque construction elements. The figures are broad estimates, often rounded to the nearest 5%. An enhanced description of the glazing system is provided including U-values and light and energy transmission factors where available.
The servicing of the building is described by the three strategies employed for heating, cooling and ventilation. If the building generates its own electricity then details are provided. The other important servicing strategy relates to daylighting, where details of the overall daylight strategy are given alongside the strategies for artificial lighting and solar control. The fundamental element of the servicing strategy in respect of this study relates to the degree of control, and a full description of the controls strategy is provided. The extent of user control is also detailed. The overall servicing strategy is summarized by a description of the operating modes in winter and summer, and at night.
The degree of intelligent control is summarized in a table which assesses each project against the functions of the building envelope. The primary functions have been re-categorized as daylight adjustment (reflection/
protection), glare control (blinds/louvres/fixed), artificial lighting control, heating control, heat recovery (warmth/coolth), cooling control, ventilation control, fabric control (windows/dampers/doors) and insulation (night/solar). The table charts whether these are performed passively or automatically, and whether there is any manual control option.
Each project also includes a range of data to enhance the written description.
Firstly, the contract sum is given as an indicator of the project value. No attempt has been made to normalize these figures to account for currency fluctuations or time variations. The total area of the building is given in square metres, along with the depth of a typical floorplate from window or window-to-core. The number of stories is provided, and basements are noted separately.
An approximate price per square metre is given in pounds sterling, again to be regarded as an indicator rather than an accurate figure for direct comparison.
As the primary objective with a large number of the schemes is to reduce energy consumption, available figures are presented for annual energy use in kilowatt hours per square metre per annum, based on delivered energy Intelligent skins
46 The case studies
consumption. These figures are then compared against typical energy use figures for a similar building type. As a further measure of environmental performance, some projects are able to quantify their carbon dioxide output in kilograms per square metre. Again all of these figures are intended to be indicative and should be read with caution.
Energy consumption can be influenced by prevailing weather conditions (which may vary from year to year), the degree of exposure and the actual hours of occupation. There are established methods to account for these variations, by normalizing the figures, e.g. BRECSU’s Normalized Performance Indices calculation. With respect to carbon dioxide emissions, it should be noted that performance in this respect is improving all the time as electricity generation moves towards cleaner generating fuels such as natural gas. It should also be highlighted that the quoted figures do not necessarily relate to treated floor areas.
The total number of sensors used in each project is given to indicate the extent of the intelligent technologies. As mentioned, 12 of the case study projects were visited as part of the study, and this is recorded. Finally, if a project has been monitored by others this is acknowledged, and the principal findings are incorporated into the description.
If the performance of the project has been monitored, the principal findings are described in the last section, including further data relating to the delivered energy consumption figures in kWh/m2per year. A total of 16 out of the 22 case studies have been monitored. Details of computer simulations and physical models used to support the design process are listed to describe the design and planning process.
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Introduction
This is the new headquarters building for Gemeinnutzige Siedlungs und Woh-nungsbaugesellschaft, one of the largest providers of social housing in Berlin.
They originally occupied a complex of buildings which comprised a 17-storey office building, together with a storey low block surmounted by a three-storey drum. In 1990–91 they decided to hold a design competition to provide themselves with additional office space. Sauerbruch Hutton won the competi-tion, proposing a slender 22-storey tower linked to the existing tower. The build-ing was completed in September 1999.