45
man-made and natural drainage systems by indiscriminate development on land that used to allow rainfall to permeate through to the groundwater. Develop- ment on f lood plains not only reduces the available land for f loodwater alle- viation but also renders those buildings vulnerable to extreme weather events, which are becoming more common as a result of climate change. SUDS strategies reduce the burden of drainage by using permeable surfaces wherever possible, or by holding water from heavy rainfall for later release into the drainage system. By careful design of ponds and lakes, SUDS not only improves the quality of wa- ter discharge to the river systems but can also provide an amenity for people and wildlife to enjoy. Development in low-ly- ing areas is equally vulnerable to rising sea levels and it is feared that many parts of the globe, including a number of major coastal cities, could become uninhabit- able within a century if levels continue to rise at the present rate. Where flood de- fenses can be constructed, they will give partial protection, but they are expensive to build and maintain.
XX ENERGY NEUTRAL DESIGN
The energy demand from the built envi- ronment has been the subject of a great deal of innovation and development in recent years. By passive solar design, thermal mass construction, superinsula- tion, and high degrees of air tightness, it is now possible to build structures that need no energy at all for space heating in most climates. By means of intelligent lighting systems, improved day-lighting, and more efficient appliances, the de- mand for electricity can be reduced significantly. Reliance on fossil fuels and nuclear energy is also being reduced as clean resources including water, wind, and light are being exploited to produce power on both macro and micro scales. Where ground conditions are favorable, heat pumps can supply the heat ing needs of entire communities, as is com- mon in Northern Europe. Where geother- mal heat is available, it makes sense to tap this free resource. Where there is no other natural energy resource, com- bined heat and power plants may be
driven by renewable biomass, as long as the environmental impact of producing these fuels is carefully considered and monitored. In many cases, the necessary plant for renewables can be housed un- derground in order to avoid using valu- able space elsewhere. When considering the environmen-
tal consequences of construction, it is easy to concentrate on the impact of the materials used and the energy require- ments of new buildings, at the expense of considering how construction projects are organized. Increasing use of off-site manufacture is yielding better buildings, as quality is easier to control in factory conditions than on-site. In developed economies, by reducing the number of persons/days on site, the burden on the transport system is reduced at the same time. Modern methods of construction have yet to be fully explored, but it is likely that significant efficiency gains can be achieved by redesigning the building process itself. More efficient use of materials, to-
gether with recycling of construction, demolition, and excavation wastes can signi f icantly reduce the demand for newly quarried materials. The use of local labor not only reduces transport emissions but also takes advantage of local knowledge of the vernacular, and equally important, ensures that the full economic gains from larger projects are received in the communities which the buildings are supposed to serve, rather than simply fueling the profits of remote companies who have won a contract on the basis of a priced bid. This suggests that contract procurement methods need to be readdressed, especially for publicly funded projects.
XX HEALTH AND SAFETY ISSUES
Sustainable construction also implies provision of safer structures. Great ad- vances have been made in the engineer- ing design of buildings in areas prone to earthquakes, and it is possible to create buildings that will not be fatally compro- mised by f looding. Yet the fact remains that vast numbers of the world’s poor- est people live on marginal land that is vulnerable to geohazards such as fire,
f lood, landslide, volcanic eruption, or earthquake. Risk assessment at govern- mental and intergovernmental levels is beginning to bear fruit in terms of disas- ter reduction initiatives, although a great deal more work remains to be done. At project level, risk assessment, design management regulations, and an in- creased awareness of health and safety have delivered very significant reduc- tions in the incidence of death and injury on building sites, but this process has an economic and therefore environmental cost, so the culture of health and safety itself needs to be kept under review. As structures and sites become saf-
er, attention is becoming focused on the health issues surrounding building prod- ucts in common use. Only since World War II have a wide variety of new materi- als and chemicals been introduced into the built environment, mostly without any knowledge of their long-term effects on human health. Some, such as asbestos, have already been found to be danger- ous and are gradually being removed. Others, such as formaldehyde, remain in widespread use despite being known to be carcinogenic. Numerous hormone disruptors and carcinogens are to be found in pesticides, fungicides, and fire retardants that are routinely added to building products, particularly finishings and furnishings. International action will be required to test these substances and to impose limits on their use if we are to prevent further bioaccumulation of toxins and eliminate “sick building syndrome.” Given the vast resources of labor,
materials, and energy expended in the construction industry, it is plain to see that sustainable construction (and renovation) is key to delivering a sustainable future for the planet. Meeting these objectives will require political agreement at all lev- els, clear strategic thinking, sound urban planning, and willingness on the part of the industry to change and adopt new ap- proaches. The growing recognition of en- vironmental, economic, and social interde- pendence, which is at the core of Modern Earth Science, constitutes our best oppor- tunity to put this into practice. PE
NIGEL GRIFFITHS is an author, consultant, and lecturer in sustainable development and construction.
Local Action Moves the World •
www.icleiusa.org
PLANET EARTH \\ CITY EXPANSION
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68