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Accentuate the positive

by John Gelder
Head of sustainability, RIBA Enterprises

It is not uncommon to describe green buildings as those 'designed to reduce the overall impact of the built environment on human health and the natural environment' (the US Environmental Protection Agency). There are a couple of problems with this sort of description. Presumably 'reduce' is meant as reduce relative to their historical precedents, rather than reduce progressively through their lifetime (which would be an interesting idea – requiring reworking of the production documents during construction, and perpetual reworking of the building during occupancy [a bit like Display Energy certificates], for example). This description therefore merely describes buildings that are less 'black' than their precedents, even if only by 1%. The description also assumes that impacts are negative, whereas buildings can of course have positive impacts on the environment (and on society and the economy). A better description would be:

A green building is one that minimizes its total negative impacts on the environment, and maximizes its total positive impacts, ideally achieving a net positive impact by the end of its life.

Is a net positive impact even possible? It is certainly a worthwhile aspirational goal, particularly as we are moving towards zero carbon for homes and the like. This article suggests how this might be managed, via the four dimensions of sustainability, best presented in a tabular format:

Attribute Minimizing negative impacts Maximizing positive impacts
Embodied impacts Minimizing negative embodied impacts Maximizing positive embodied impacts
Operational impacts Minimizing negative operational impacts Maximizing positive operational impacts

This table can be applied to any relevant attribute – perhaps the 13 used in BREEAM's Ecopoints scheme, or the 49 used in BREEAM New Construction. Here we will look at how the table might be applied to a handful of broad product selection criteria – climate change, waste, air pollution and resource efficiency. The tabulation is in no way complete.

Climate change
Climate change Minimizing negative impacts Maximizing positive impacts
Embodied impacts Minimize embodied energy and hence CO2 emissions. Refer to the energy ratings in third-party product certification schemes such as BRE Environmental Profiles, EU Ecolabels, and IBU Environmental product declarations for assessments of branded products. Refer to the BRE Green guide to specification, for assessment of generic systems and products.

Source products with a complete local supply chain (extraction to delivery), to minimize embodied transport, particularly for massive or bulky products.
Select systems and products that maximize energy production and embodied CO2 absorption, e.g. through techniques such as those in the box below. This should be picked up in the third party schemes mentioned in the box to the left. This should lead to use of timber framing and straw bale walling, for example.
Operational impacts Minimize CO2 emissions in the site's energy mix – select domestic suppliers accordingly. One of the 15 UK suppliers had zero kg CO2/kW•h in 2007-8, and two had less than 0.3. The three worst performers in this respect had more than 0.5.

Minimize consumption of energy, e.g. by boilers, space heaters, fans, air-conditioning units, tumble dryers and lights, by avoiding these products where practicable (e.g. by providing a well-ventilated drying room in lieu of tumble dryers), and by selecting energy-efficient ones otherwise, by reference to their European Energy Labels, or to some other scheme.

Minimize design features that increase the consumption of energy, e.g. avoid single glazed curtain walls, west-facing windows, or thermal bridging.

Minimize consumption of energy at end of life, i.e. to demolish, recycle (especially compound materials) and dispose of waste.

Minimize any consequential increase in consumption of energy at end of life, e.g. downcycled concrete requires virgin reinforced concrete to be made, with associated energy consumption and CO2 emissions.
Maximize absorption of CO2, e.g. through the use of materials such as olivine concrete, magnesium silicate cement, milk paint, lime wash, and smart paint. Absorption of CO2 can also be achieved through planting, especially of plants that offer maximum carbon sequestration, e.g. through phytolith carbon held in bamboo and similar grass crops, and through selection of particular varieties of species such as pines.

Maximize production of energy on site, e.g. through use of photovoltaics, solar water heaters, windmills (which would be classed as 'eco-bling' below a certain size), conservatories. The site could even sell power to the grid, at least some of the time.

Maximize production of fuel, e.g. generate gas through collection of methane from the processing of waste from dry toilets, and harvest urine to produce fuel.

Maximize use of, e.g. washing lines, thermal insulation, double glazing, light shelves, operable windows, thermal mass, and phase changing materials, to minimize consumption of energy.

Maximize production of energy at end of life, e.g. by disposing of wood waste and plastics as fuel if all else fails, ideally on site.

Maximize any consequential reduction in consumption of energy at end of life, e.g. recycling aluminium minimizes the need for virgin aluminium, saving large amounts of energy consumption and CO2 emissions.
Waste Minimizing negative impacts Maximizing positive impacts
Embodied impacts Minimize embodied waste, e.g. quantity of materials discarded after metals extraction and processing (spoil heaps and the like). Refer to waste ratings in BRE Environmental Profiles, for example.

Minimize wasted energy in production, e.g. avoid products made in factories that burn off waste gas or discharge heated water.

Minimize nuclear waste by avoiding products from high-nuclear nations. The 2004 'primary energy supply' figures from fact sheets show that 12 European countries had higher nuclear content than the UK's 9%. The three worst performers in this respect were France, Lithuania and Sweden, all at 37% or more.
Maximize the recycled content of selected systems and products, e.g. by selecting stainless steel, aluminium, cellulose fibre insulation, glass, and some plastics products.

Maximize the use of renewable materials in selected systems and products, e.g. wood, plant fibres, sheep wool.

Maximize use of products made and delivered using renewable fuels.

Maximize use of re-used products such as second-hand timber and reconditioned windows.
Operational impacts Minimize production of waste, e.g. arising from conventional sanitary services, paper-handling equipment, food-handling equipment.

Minimize increased creation of waste, e.g. do not over-size components, do not oversupply of equipment (built-in waste).

Minimize production of waste at end of life, e.g. avoid difficult-to-recycle products such as plasterboard, compound products, old technology equipment, asbestos, CFCs.

Minimize increased creation of waste at end of life, e.g. do not specify glued or welded jointing and fastening, cement mortars, bonded multi-material products.

To minimize nuclear waste, minimize nuclear power in the site's energy mix – select domestic suppliers accordingly. Three of 15 UK suppliers had zero nuclear in their mix for 2007-8, and five had 5.5%. The two worst performers in this respect had 24.8% and 28.1%.
Maximize consumption of waste on site, e.g. through composting toilets, reed beds, methane-based power. Boilers could use wood waste or methane collected from composting toilets. Gardens could use waste water for watering.

Maximize use of, e.g. modular design for modular materials, just-right servicing, water-efficient products, to minimize creation of waste.

Maximize recycling at end of life, e.g. use steel beams, doors, antique fireplaces.

Maximize down-cycling at end of life, where recycling isn't viable, e.g. in situ concrete, PVCs, crushed brick, carpet tiles.

Maximize use of, e.g. screws or bolts rather than glues or nails, lime mortars, deconstructable equipment, and durable systems and products, to minimize creation of waste at end of life.
Air pollution
Air pollution Minimizing negative impacts Maximizing positive impacts
Embodied impacts Minimize embodied air pollution, i.e. generated during extraction, product manufacture, transport etc. Refer to National Atmospheric Emissions Inventory.

Refer to the air pollution ratings in BRE Environmental Profiles, for example.
Select products made using closed-loop manufacturing, though it is unlikely that air pollutants will be used in this way – they'll merely be collected rather than recycled.
Operational impacts Minimize production and release of pollutants, e.g. avoid urea formaldehyde foams, VOC-containing paints and solvents, wood/fossil-burning heaters, mould, plasticized PVC.

Minimize increased production and release of pollutants, e.g. avoid carpets (dust mites etc), unflued gas fires, dampness, products requiring chemical cleaners or vacuuming.

Minimize end-of-life pollution, e.g. most products will create pollutants (uncontrolled wastes) in their demolition, reuse and disposal.
Maximize removal of pollutants, e.g. through use of exhaust fans, absorptive paints, filters, asbestos-cement encapsulation, bake out, catalytic conversion, natural light, radon sinks.

Maximize use of, e.g. VOC-free paints and solvents, radiant heaters, timber flooring, CO monitors, controlled combustion heaters, products requiring aqueous cleaning, physical termite barriers, self-finished products, to minimize production and release of pollutants.

Maximize conversion of pollutants to harmless chemicals, e.g. through photocatalytic paints, and selective indoor planting (courtesy NASA).
Resource efficiency
Resource efficiency Minimizing negative impacts Maximizing positive impacts
Embodied impacts Minimize resource consumption through minimizing embodied water, minerals and fossil fuels in the site's systems and products. Refer to resource efficiency ratings in BRE Environmental Profiles, for example.

Use lightweight products rather than functionally equivalent but more massive ones.
Maximize resource production by selecting products from supply chains that maximize the production of water, power and fuels, and maximize the recycling of waste water, minerals and fuel. Manufacturer's annual corporate social responsibility reports may be of use here.
Operational impacts Minimize the site's water consumption, e.g. through xeriscaping (perhaps not necessary outdoors in the UK!), and through use of water-efficient shower heads and the like.

Minimize the consumption of fossil fuels – see Climate change.
Maximize generation of water, through collection of rain water and processing of waste water.

Maximize supply of mineral resources, through recycling of waste glass, metals and plastics for example, and especially of IT equipment (e-waste), which is loaded with rare metals. Harvest urine to produce fertilizer – this will also help minimize eutrophication.

Maximize production of power and fuels – see Climate change.

Finally, an obvious positive impact to round off on, for biodiversity. The site could support and encourage native flora and fauna, through bee houses, bird boxes, bat boxes, and selective planting of, e.g. native meadow flowers. Many of these flowers will also benefit butterflies or moths. Planting in general can be maximized (e.g. green roofs and vertical planting), and the site could be developed as part of a wildlife corridor.

There's lots of advice out there on how to eliminate the negatives. It is time now to accentuate the positives.

  • BRE, BREEAM New Construction: Non-domestic buildings – Technical manual, BRE Global, 2011
  • Dickie, I. and N. Howard, Digest 446: Assessing environmental impacts of construction: Industry consensus, BREEAM and UK Ecopoints, BRE, 2000
  • Gelder, J., Building product selection, OECD/IEA Joint Workshop: The design of sustainable building policies, June 2001, Paris.
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September 2011




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