Download components, materials and technologies in practical pursuit of

CIB World Building Congress, April 2001, Wellington, New Zealand
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COMPONENTS, MATERIALS AND TECHNOLOGIES IN PRACTICAL PURSUIT OF
SUSTAINABLE BUILDINGS
HENRY SKATES+, BRIAN NORTON*, AND JOHN STOREY+
+
Centre for Building Performance Research, Victoria University of Wellington,
Wellington, New Zealand.
*Centre for Sustainable Technologies, University of Ulster,
Newtownabbey, BT37 0QB, N Ireland
ABSTRACT
The strategic issues underlying the selection of appropriate technologies that contribute to the
environmental sustainability of buildings are discussed. Specific examples of building technologies
that facilitate the goal of achieving sustainability are described. Design objectives are identified as
having a significant influence on the selection of sustainable technologies, while value judgements
often allow for the inclusion of technologies that have adverse environmental impacts. Six houses,
three from New Zealand and three from the UK are discussed with regard to the choice of sustainable
technologies.
KEYWORDS:
Sustainable buildings; renewable energy; material use; environmental impact; life cycle analysis.
INTRODUCTION
Buildings worldwide have individual and collective, direct and indirect, impacts on the environment
both present and future as illustrated in Fig. 1. Each building, by occupying land, alters the ground
and vegetation, changes water courses and wildlife habitats and, in both construction and use,
consumes resources, labour, materials and fuel for power, heating and maintenance. Within the
European Union it has been estimated that buildings consume about 40% of energy, produce 30% of
carbon dioxide emissions and generate 40% of waste materials. Sustainability, in this instance, means
“meeting the needs of the present without compromising the ability of future generations to meet their
own needs” (WCED, 1987). Sustainable construction is thus the “creation and responsible tenure of a
healthy built environment based on resource efficient and ecological principles” (Kibert, 1994). This
is accomplished through the adoption of a holistic view of the world and human interactions with it,
under which every function is cognisant of and within the limits of both the local and global
ecosystems. This perspective has been summed-up by the phrase “think global, act local”.
Sustainable buildings are characterised over their period of use by:
•
Consuming minimal resources (materials, energy and water).
•
Efficiently using environmentally benign materials and energy.
•
Minimising both direct and indirect waste and pollution including good indoor and outdoor air
quality.
•
Integrating harmoniously with the natural environment.
•
Contributing by location and services to a sustainable urban form and transport system.
•
Being safety constructed and healthy to use.
•
Facilitating social development.
•
Being capable of adapting to special needs.
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These characteristics relate to diverse aspects, differently measured, of a building’s commissioning,
design, construction, occupation and demolition. An optimised strategy thus has to be underpinned by
subjective value judgements as to the importance of each objective.
Fig. 1. Global-Local Links and Impacts of Buildings
Broad strategies to achieving sustainable buildings are summarised in Table 1.
Table 1. Strategies Leading to Sustainable Buildings
Objective
Strategy
Use less: energy, materials,
water, and land.
Conserve: natural environment,
bio-diversity.
Maintain: healthy indoor
environment, accessible
outdoor environment.
Reuse, recycling, use of renewables, loose fit, long life,
efficient use, life-cycle design, renovation, low maintenance.
Optimise land use, prevent pollution, avoid regrading, and
encourage ecological harmony.
Healthy materials, adequate ventilation, breathing skins,
provision of public transport, amenities, services, noise
abatement, socially inclusive access.
IMPERATIVE CRITERIA
Sustainable buildings should use technologies, materials and energy to meet the following criteria:
•
Low energy use in the occupation of the building.
•
Low embodied energy materials, processes and products should be used where possible.
•
Selection should be based on the source and origin being managed sustainably and where
extraction, processing and manufacture conform to best practice environmental management.
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•
•
•
•
•
•
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Anticipate the needs of building users – facilitate changing requirements.
Wherever possible recycled or reused materials, products and components should be used in
construction, refurbishment and repair and all surplus materials on site should be separately
sorted and recycled or incorporated in the building or reused to minimise waste.
The building should be designed to optimise opportunities on its proposed site, taking into
consideration aesthetic and climatic factors as well as energy and material resources.
Materials, which do not incorporate toxic; solvents, chemicals, preservatives and synthetic
resins, should be used to safeguard the health of construction workers and building occupants.
Renewable technologies should be utilised where appropriate for electricity generation, heating
and cooling.
The construction of a building should use local materials, requiring as little transportation of
resources as possible.
Be designed to be as self sufficient as possible.
The implementation of sustainable buildings requires a wide-range of broad measures that may be
grouped as shown in Table 2.
Table 2. Actions in Support of Sustainable Housing
Design
Considerations
Consider
environment
impacts of
materials.
Optimise design
with respect to
construction
logistics.
Design for
durability, reuse,
re-cycling and
repairability.
Design for low
resource use.
Adaptable design.
Life-cycle
approach to
design.
Set sustainability
criteria in design
brief.
Construction
Process
Reduce the
environmental
input of site
operations,
supply logistics
and materials
use.
Minimise,
manage and
recycle site
waste.
Retain soil,
vegetation
and
watercourses
where
possible.
Avoid
damage and
pollution.
Broker
demolition
materials.
Technology
Selection
Government
Intervention
Base product
development on
life cycle cost
rather than initial
cost.
Improved energy standards.
Minimise
pollution and
energy use in
manufacturing,
use and
demolition.
Exclusively best practice in regulations.
Reliable, accurate
product ecolabelling.
Durable low
maintenance and
repairable
products.
Reuse/recycle of
materials.
Shorten
environmentally
benign product
development time
to market.
Planning to promote public transport use.
Promote the use of healthy materials.
Retention of natural ecology required by
building codes.
Promote eco-labelling of buildings, their
sub-systems and components.
Universal labelling of all products with full
disclosure of all by- products, waste etc..
Promote use of brown-field sites.
Promote common life-cycle analysis
methods and databases and provide
incentives for move to life cycle
procurement.
Promote ethical investment and
development strategy.
Funding sustainable initiatives.
Educate and inform public of issues.
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As may be seen, governmental actions, and as a prerequisite, public demand, to promote economic
and social sustainability are explicit. There are also crucial obligations on designers and constructors.
This paper, however, focuses on building technologies that can facilitate the sustainability of
buildings.
TECHNOLOGY SELECTION
The selection by designers of building materials, products and component technologies can be
conservative, which hinders the introduction of new technologies. Though often arising from
unproven long-term performance of innovative systems, this conservatism is driven both by
familiarity - by using what was used before, and by the designer’s actual or perceived expectations of
clients’ needs. Major clients are thus, by explicit communication of their wish for sustainable
buildings, able to encourage the development and implementation of underlying technologies. Central
and provincial government can be particularly successful in this activity, as they are often the largest
clients. For example, in the 1970's and 1980's the UK central government’s use of co-ordinated
procurement based on performance specifications has been shown (Cheetham, 1997) to reduce
innovation market risks for the manufacturers of building components.
A particular technology will be a useful contributor to the overall sustainability of a building only for
a specific set of contexts. The latter will vary depending on building use, location, climate, competing
technologies, economic and social acceptability and regulatory imperatives. Selection must therefore
commence with consideration of the broadest range of generic technologies on the basis of life-cycle
environmental and economic analyses. In reality, seeking to produce buildings that are benign
environmentally and viable economically is often a pragmatic qualitative process. For small projects
the additional cost of further design work to attain more unequivocal sustainability is difficult to
justify. The outcomes of pragmatic sustainable building design are often useful exemplars despite
their inherent compromises (Skates et al, 1998). For those in developed countries, generic and
technology-specific time-limited life-cycle analyses are available (see, for example, for solar water
heaters, Smyth et al (2000)). For developing countries, not only are they not available, but also the
appropriate underlying public policy consensus is only now being developed. In particular in
developing countries it is important, as noted by Muttagi (1998) that the pursuit of sustainability in
buildings, and also in a wider context, does not reinforce economic disparities or instigate unwanted
patterns of social change. The widest open participation in making underlying value judgements is
thus essential. Vernacular or traditional building design solutions are frequently either inherently
sustainable or the most sustainable within pertinent economic parameters. Where this is the case, in
broad terms, the only additional technologies required are those that meet needs unsatisfied by
traditional means.
TECHNOLOGICAL EXAMPLES
Consider the following specific examples of sustainable domestic buildings in the New Zealand and
United Kingdom climates respectively. They each subscribe to technologies that support
sustainability set in the context of a passive solar design underpinned by good practice in energy
conservation but in each case value judgements have been made with regard to the inclusion of
additional technologies.
New Zealand Examples
The objective of the Southpark Solar Vision home designed for a specific client by architect Roger
Buck is a passive solar house with a range of other energy-saving features included. The primary
passive solar strategy is direct gain windows with high thermal mass to store collected energy and
higher than normal insulation levels. The house is primarily of concrete construction including
floors, walls and roof. This is combined with a fairly open plan to expose as much of the structural
mass surface area as possible to sunlight. Innovative sustainable technologies include shower trays
that recover heat from waste hot water and a gas fired sterling engine producing electricity and hot
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water for under floor heating and provision has been made for solar hot water heating. Rainwater is
collected and taken to an existing irrigation system. Whilst achieving the design objective of an
energy efficient house, the building also uses a number of less than environmentally benign
materials to achieve this objective. Take for example the high-embodied energy of concrete (Alcorn
1996) or the hazardous waste by-products in the production of PVCu as used in the window frames.
Clearly there are environmental impacts other than renewable energy, which need to be considered
in achieving a sustainable building.
The eco-friendly home in Waitakere City was designed as a speculative development to look like a
‘normal’ New Zealand home. The objective here was maximum desirability and while energy
efficiency was not top of the agenda, it has been given reasonable consideration. Low mass walls are
used on a concrete floor slab. Sustainable technologies included in the design are reusable rainwater,
low water use and energy efficient appliances. Low environmental impact sustainable materials are
used throughout the house and the health and wellbeing of the occupants has been addressed with
attention being given to indoor / outdoor flow, indoor air quality and reduced electromagnetic flux. A
heat pump air conditioner is used to provide heating in winter and cooling in summer (cooling is
required in the Auckland climate in the summer). An additional heat pump is used to provide hot
water heating. In the effort to make this home look normal, some basic passive solar design principles
have been overlooked. Typical New Zealand houses have up to 40% of the wall area as glazing on all
elevations. This house is no exception. However, due to inappropriate levels of glazing, solar control
glass has had to be used on the north elevation. This will reduce the benefits of winter sun. The
house was on public display for six months before being offered for sale. The house sold easily,
reinforcing the fact that the design objectives were clearly met however compromises have been made
in the passive solar design strategies employed, resulting in potentially increased energy use.
The objective of the Wellington eco house was to address contextual and cultural sensitivity and cost
as well as environmentally conscious design in a local authority house for rent. Due to the unknown
lifestyle and social needs of future tenants, it could not be assumed that occupiers would be
committed to, or even be aware of environmental ideas (Storey 1994). Complicated environmental
control regimes or mechanisms that require significant maintenance were therefore rejected in favour
of automatic or simple operating systems. Robust materials such as concrete masonry walls and
floors were chosen for their long life expectancy and resistance to wear and tear. Sustainable
technologies include a Trombe wall on the north façade and direct gain windows and skylights.
Natural ventilation along with ample thermal mass in the floors and walls is used to control summer
overheating. Like the eco friendly house in Waitakere, heat pumps are used for domestic hot water
and air conditioning. A night storage heater supplements the heating from the air heating system. A
separate granny flat also incorporates a roof mounted solar water heater. Water conservation is
addressed, as are health issues. Again like the Waitakere house, the Wellington house was on public
display for six months and many visitors were disappointed to learn that the house was not for sale.
Clearly again, the house met the design objectives of being a desirable home to rent, being
contextually, culturally and environmentally sensitive, but certain aspects of the design are
questionable in a sustainable context. The extensive use of poorly insulated concrete masonry not
only has high embodied energy but subjected to an intermittent heating regime common to many
households today, may actually increase overall energy use. This is an inherent problem when
designing for an unknown user.
United Kingdom Examples
The Vale house at Southwell in Nottinghamshire, England sets out to be autonomous. The only
connections to mains services are for telephone and a two-way electricity connection. The house
design was predicted to rely only upon the resources of the land, which it occupies. Among the many
technologies employed are super-insulation, on-site rainwater collection and filtering for domestic use
and a sewage composter for waste. A heat-recovery mechanical ventilation system is used to preheat
incoming ventilation air and thirty-six photovoltaic 60-Watt panels largely meet electricity demand.
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These additional technologies combine to make the house autonomous thus achieving the design
objectives. The house is an excellent example of what can be achieved but this comes at a price.
The space required for the sustainable technologies accounts for approximately 30% of the floor area
and represents a substantial initial cost overhead; in addition the photovoltaic array occupies a portion
of otherwise useable garden space. This necessity of autonomy demanding so much space is a
paradox in terms of sustainability (Hawkes, 1995). There are limits to the density at which houses
like this can be built with sufficient resources to meet their needs.
The Solar House in Magherafelt in Northern Ireland was designed to have net zero carbon dioxide
production from the site, hence the acquired name “Zero C02 House” (Anon, 1996). The house is
built on reclaimed land, and like the Vale house, uses low heat-loss glazing, has high levels of thermal
insulation, uses heavyweight construction to provide high thermal mass and has a ventilation system
with heat recovery. It also has wood burning facilities for heating using site-grown timber (In the case
of the Vale house the trees felled to make room for the house were not replanted and were thus a
finite resource). This house too has grey-water recycling through a reed bed and pond system, but the
water is only used for the garden and car washing. The inclusion of a single-phase mains parallel
wind turbine is designed to meet demands for electricity consumption. In addition, the house makes
use of evacuated heat pipe solar collectors for heating domestic hot water. All in all the cost of the
additional sustainable technologies represents approximately 25% of the total building cost. Again
this house meets the design objectives, but also like the Vale house, there are clear-cut restrictions to
replicating the Zero C02 House in the mass housing market.
The Skates’ house in Antrim, Northern Ireland was designed with a pragmatic approach balancing
affordability, buildability and sustainability with the main design aim being year round low cost
thermal comfort (Skates and Norton, 2000). It too was built on reclaimed land and makes use of
passive solar design principles. Like the previous examples it incorporates low heat-loss glazing, high
levels of thermal insulation and mechanical ventilation with heat recovery, but instead of having high
thermal mass, relies on a highly efficient fast response heating system to provide even annual and
diurnal internal temperatures. Some spaces have been allocated to easily accessible service ducts to
allow for the inclusion of additional sustainable technologies such as solar water heating and grey
water recycling as they become attractive economically. The cost of building this house was on a par
with traditional construction even though a number of innovative construction methods and materials
were incorporated. The adoption of a pragmatic stance, which balances affordability, buildability and
sustainability, requires that the design make use of both sustainable materials and less than benign
materials such as concrete and PVCu, but only in limited amounts, and only because it was prudent
either financially or technically to do so.
CONCLUSION
Sustainable buildings are a contribution to the achievement of holistic environmental sustainability.
This paper discusses the strategic issues underlying the selection of appropriate technologies that
contribute to the environmental sustainability of buildings. Specific examples of building
technologies and the goal of achieving sustainability are described. The characteristics of the lifetime
use of sustainable buildings are identified. These characteristics relate to diverse aspects, differently
measured, of a building’s commissioning, design, construction, occupation and demolition. Six
houses, three from New Zealand and three from the UK are discussed with regard to the choice of
sustainable technologies. Each house seeks to contribute in its own way to the achievement of
holistic environmental sustainability. In reality, an optimised strategy is often compromised by
subjective value judgements as to the importance of each objective. There has, on occasion, been a
tendency to pursue the goal of sustainable buildings through self-sufficient or autarkic solutions.
While such exercises are interesting, and often have considerable educational value showing what is
possible rather than what is currently viable, they do not, by their individual nature, often address
some of the mainstream issues such as replicability. It is only after practical sustainable technological
choices have been made including adopting appropriate measures to minimise building energy, that
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decisions need to be made for example as to whether energy will be produced at the building (by solar
heating, photovoltaic, wind generation, etc) or purchased from utilities. Site factors, economic
viability, and environmental life-cycle analysis rarely combine to lead to a self-sufficient approach,
rather an optimal mix emerges. Design objectives are identified as having a significant influence on
the selection of sustainable technologies, while value judgements often allow for the inclusion of
technologies, components or materials that have some adverse environmental impacts.
The house designs discussed strive to be sustainable environmentally. Those designs that achieved a
comparable initial cost to prevailing costs for similarly-sized dwellings, did so via pragmatic
compromises in materials and technology selection. Those designs (such as the "Vale" and "Zero
CO2 House") which tend to be self-sufficient or autarkic solutions have a much higher initial cost.
Whilst the energy use of the latter designs is certainly environmentally benign, they are not readily
replicable. Widespread use of the large plot size required would lead to low urban densities leading
to unsustainable transport use. Thus the adoption by house-builders of a pragmatic but leading-edge
approach to sustainable design can be concomitant with commercially-viable site densities and more
broadly sustainable urban forms.
REFERENCES
Alcorn, A. (1996). Embodied Energy Co-efficients of Building Materials, Centre for Building
Performance Research, Victoria University of Wellington.
Anon., (1996). Zero C02 House, EDS 70, Department of Economic Development, Belfast, Northern
Ireland.
Cheetham, D. W. (1997). The use of performance specification in the procurement of building
components. Proc International CIB Symposium W92 on Procurement, Montreal, Canada, pp. 61-70.
Hawkes, D. (1995). Realising the autonomous house, The Architects Journal, Vol. 201, pp. 37-39.
Kibert, C. (1994). Proceedings of the First International Conference on Sustainable Construction,
Tampa, Florida, November, pp
Muttagi, P. K. (1998). Sustainable Development - A third world perspective. Sustainable
Development and the Future of Cities (B Humm and P K Muttagi, Eds.) Intermediate
Technology Publications, London, pp. 1-18.
Skates, H. and Norton, B. (2000). Sustainable by Degrees: An Irish Example, Proceedings of the
CAA/NZIA Vision Re Vision Conference, Wellington, New Zealand
Skates, H., Norton, B. and Mannis, M. (1998). An Affordable Sustainable Housing Design for the
Irish Context, Proc 5th World Renewable Energy Congress, Florence, pp 1439-1442.
Smyth, M., Eames, P. C. and Norton, B. (2000). Life cycle assessment of a heat retaining integrated
collector/storage solar water heater (ICSSWH). Proceedings of the 5th World Renewable Energy
Congress, Brighton, UK.
Storey J. B., (1994). Eco House: An Environment, User, Context Friendly Home, Proceedings First
International Conference on Sustainable Construction (CIB Task Group 16) pp 27-36, Tampa
Florida.
World Commission on Environment and Development (WCED) (1987), Our Common Future - the
Brundtland Report, Oxford University Press, Oxford.