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For the past eight years the Planning and Building Unit within the Department of Education & Science has been using an approach known as DART to develop sustainable and efficient energy usage in educational buildings. This acronym focuses on four key areas, namely; Design, Awareness, Research, and Technology.
Schools, by their nature, present particular limitations from the point of view of energy conservation. They have short operational hours and a lack of building management specialists on site. Energy conservation is simply not a core function. This means that systems must be robust, reliable and relatively simple and automated. The Planning & Building Unit have taken a holistic approach and have developed their technical guidance on energy efficiency in school designs as an integral part of their suite of Technical Guidance Documents, which can be seen at www.education.ie
These guidelines are developed not just for the building services engineers but also the other members of the design team. A complete design team approach from project conception is encouraged. There is particular emphasis on the elimination of over-design, improved thermal envelopes and improved passive solar design, natural ventilation and day lighting. The elimination of over-design and specification is important in terms of energy efficiency; there is no point developing sustainable strategies when the project has been over-designed in the first place. Any additional over-design costs can be utilised to promote energy efficient elements.
The design teams are encouraged to let their designs take into account microclimate, the building form and orientation of spaces, the thermal performance characteristics of the building, the occupancy trends and restrictions on pollutant emissions. They should also be aware that energy efficiency strategies can support each other or can conflict and thus individual measures should not be considered in isolation.
The incorporation of low energy design has been done on a hybrid basis by maximising natural resources and utilising technologies. Maximising natural resources involves focusing on areas such as natural ventilation, passive solar design, day lighting and reducing infiltration. The involvement of the building services consulting engineer from the outset is critical in developing issues such as site usage, plan form, orientation, passive ventilation and passive solar strategies and day lighting.
A good passive solar strategy which obviously depends on site issues can produce up to a 25% saving on early morning heat up demand by maximising the use of early morning sun for passive heating.
Ventilation is provided by natural means with the design teams encouraged to make certain that the window design ensures adequate natural ventilation at high and low level is provided without any draughts.
Good natural daylight in a learning environment is valuable. Studies have shown that daylight can positively affect health and productivity in a work and learning environment and classrooms are both a working environment for teachers and a learning environment for children. All teaching spaces and habitable rooms must have natural daylight as their principal source of light. The geometry and distribution of glazed areas should be carefully designed to provide a high level of natural light while avoiding glare and ensuring a good quality day lighting distribution in the room. The average day lighting factor should be in the range of 3.5 to 5.5 %. The use of solid panes in the window geometry is discouraged unless the above standards are achieved. All teaching areas and habitable rooms must have a horizontal vista and view of the outside environment. To maximise efficient use of glazing, and to provide for services distribution on external walls, window sill heights should be a minimum of 800mm above the finished floor level. The window head height should be a minimum of 2100mm above finished floor level for the primary windows in a teaching space. The use of sun tubes is also promoted given their appropriateness for use in schools based on their lighting capabilities, good thermal and security characteristics.
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