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Passive and Active Buildings In application Author
Professor Ken Agyekum-Kwatiah
Project
The Docklands Shopping Centre (London)
Date published
2nd February 2018
Available at
University of East London
Via Linkedin
ICEPE-UK
ResearchGate
Issuu
http://professorken.wixsite.com/professorken-uk/useful-links-downloads
Content Introduction Passive Buildings Active Buildings Application to the Docklands Shopping Centre project Conclusion References
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Passive and Active Buildings In application Introduction The building industry is notorious for being greenhouse gas emission nuisance. Sustainable design alternative (incorporating passive and active designs) offer a better alternative (Lallanilla, 2015). Integrating green design concepts would reduce the consumption of electrical energy significantly both in cost and maintenance (Javeshkumar et al, 2016). Green design (Figure 2, 1b and 1c) minimises harmful effects on human health and the environment by protecting air, water, and earth through eco-friendly building materials and construction practices (which involves passive and active design concepts) (Craven, 2017).
Passive Buildings Passive buildings use ambient energy sources such as daylighting, natural ventilation, and solar energy. They use architectural considerations like shape, size, orientation, form, air movement, site conditions, layout, solar radiation and & the natural environment for heating, cooling, lighting and ventilation (Figure 1). A Passive House project maximises the energy efficiency of the basic building components (including walls, roofs, windows, and floors) and the utility systems (including plumbing, electrical and mechanical) (Graham, 2003).
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Passive solar buildings would typically have south-facing-side windows (Figure 3a) to absorb direct sun energy for warming during winter (Figure 3). In summer it relies on a system of shading or an overhang in order to cool the building (Greenpassivesolar, 2018). Further cooling can be achieved by using green roofs, and walls as well as shady plants/trees (Figure 1b and 1c). Overheating can be prevented by minimising solar gains and by reducing internal heat gains. This can be achieved by using outdoor cooler air to ventilate while using the thermal mass to store excess heat. However, care must be taken to avoid noise and contaminated air entering. Also unlike active schemes, careful control regimes are required for achieving ‘comfort ‘objectives, in particular, as its difficult to ensure specific temperatures or humidity levels. Consequently, an accurate performance prediction is difficult.
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Active Buildings Active buildings (Figure 4) are similar to passive designs. However, they incorporate renewable energy such as solar power, and wind power to further reduce emissions. This can lead to zero-energy-buildings as there is a reduction in GHGs1 emissions, energy demand and embodied energy. Also, excess energy is fed back to the grid. The design may integrate heat pumps, radiant panels and electric lights powered by a renewable source. They are Hybrid buildings. An equilibrium position reflecting a good combination of passive and active strategies can minimize energy, materials, water, and land use.
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Greenhouse gases
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An optimised passive building would require less active systems elements necessary for achieving an ‘equilibrium’ /hybrid balance. An optimized building design can reduce the heating load by up to 12% per building total volume (Stevanović, 2013). The massing and layout of buildings can produce self-shading effects to enhance ventilation and natural lighting.
Application to the Docklands Shopping Centre project According to Aldawoud (2013), square-shaped atrium2 ((Figure 9) has the best performance with more energy savings achievable in low rise structures with larger glazing to roof ratio. Relying on complete natural ventilation would demand a taller building as air speed is faster at greater heights. Sadly, such factors could force the centre into shapes that defies the consistency of its neighboring architecture and possibly restrict its ‘resort-feeling’ achievement that would typically characterize a modern shopping centre of its potentials. While changes to the building orientation, aspect ratio, and shape factors could yield energy savings of 1-5% (Mingfang, 2002: Inanici, and 2000), this could provoke a compromise with the designers desire to use the water body to achieve specific aesthetic values.
However, the hybrid concept can add significant design and comfort value in several ways: Light shelves and external reflectors (Figure 5) can be used to extend light reach deeper into rooms; Shoji (Figure 6) would aid light traveling through interiors and interior walls can be retracted for more light during the day; and fibre optics translucent concrete3 (Figure 7) integrated into wall members can admit light into interiors. Also, roof monitors (Figure 10), lightwells (Figure 8), light tubes, sunlight transporters, bottle walls and clerestories can afford the shopping centre a wide range of optional methods for gaining interior passive lighting4,
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An open/covered top space within a building larger than lightwells light transmitting concrete 4 Achieved using architectural elements to light interiors with sunlight 3
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and comfort.
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Conclusion Presently, green architecture (that incorporates passive and active designs) offers the best solutions for sustainable development which represents the global answer to the environmental, economic and social challenges of our time. The integration of green architecture into this project is not only commendable but also conforming to its existing neighbours.
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