MODIFICACION DEL SISTEMA INMOBILIARIO DEL DERECHO COMUN POR LA EQUIDAD

2.6.3.1 MATERIALS

Most construction materials are a finite resource and will eventually be exhausted. Many already are. Local British sources of Portland stone, which has been used as a cladding material for many years, have been exhausted or the quarries closed and it now has to be obtained from the Continent. Certain colours of terrazzo marble, once popular in the 1960s, are no longer available as entire mountains in Italy have been levelled. The use of terrazzo has now been superseded by the increased use in solid marble and granite although it will only be a matter of time before these sources are similarly exhausted.

Even organic materials are not immune. Brazilian Rio Rosewood, which was very popular for making high-quality furniture in the 1960s, is now so endangered that it appears on the Control in Trade of Endangered Species (CITES) list as being illegal for fear of extinction. Mahogany is also on the fringes of being listed and it is widely reported that there are no longer any legal sources for the supply of the true Swietenia mahogany.

An example closer to home is the UK’s reliance upon imported timber having used up its own supply. The history of timber production in the UK is an interesting one which has seen the rapid depletion of forests from approximately 90 per cent forest coverage at the time the Romans arrived to a low point of less than 5 per cent of land coverage at the early part of this century. Timber was first imported after the Great Fire of London and in 1668 it became necessary for Acts of Parliament to be passed to create forest reserves like the New Forest in Hampshire to try to arrest the situation. World War I saw timber in short supply again and resulted in the birth of the Forestry Commission as a Government Agency in 1919. World War II resulted in timber shortages again and the emergency created the major post-war plantation of quick-growing conifers.

Humankind has a history of failing to adequately consider the impact that its activities are having on the resource base and examples are easy to find.

2.6.3.2 BENCHMARKINGENVIRONMENTALIMPACTS

In order to be able to assess the effect that we are having upon the environment as a result of our activities a scientifically rigorous and consistent method of analysis and bench marking is required. Such a method would have to attribute units of measurement to each environmental impact and in turn to relate these back to a datum to render the results meaningful on a human scale.

The Building Research Establishment (BRE) has undertaken more work than most in this area. It has developed Envest, an environmental estimating software tool which attributes Ecopoints to environmental impacts, with 100 Ecopoints being equivalent to the environmental impact of the average UK citizen. Using a variety of comparison models and mathematical techniques Ecopoint values have been attributed to building materials and systems, and it I

PART 2, SECTION 6

The Surveyors’ Construction Handbook Part 2, Section 6 (revised 10/01) Effective from 1/12/01 Page 5

is now possible, via the software package, to calculate the total Ecopoints score for building types, building operations, refurbishment and custom use.

From this data one form of construction can be analysed against another. It is also possible to quantify the decision-making process using environmental criteria, not only by building type and the method of construction that should be used but also the decision whether to build new or to refurbish.

Environmental Impacts

In undertaking the assessment of environmental impacts and attributing Ecopoints values to various activities and products, the following must be considered carefully:

• climate change;

• fossil fuel depletion;

• ozone depletion;

• human toxicity to air and water;

• waste disposal;

• water extraction;

• acid deposition;

• eutrophication (or over enrichment of water courses);

• ecotoxicity;

• low-level ozone creation (summer smog); and

• mineral extraction.

All these factors have been considered, quantified, compared and weighted in relation to the impact associated with a typical UK citizen and are shown in table 1.

Table 1: Environmental Impact of UK Citizens

Issue % weighting Characterized impact

associated with a typical UK citizen

Climate change 37.8 12300 kg CO₂ eq. (100yr)

Fossil fuel depletion 12.0 4.09 tonnes oil eq.

Ozone depletion 8.2 0.286 kg CFC11 eq.

Human toxicity to air 7.0 90.7 kg toxicity

Waste disposal 6.1 7.19 tonnes

Water extraction 5.4 418000 litres

Acid deposition 5.1 58.9 kg SO₂ eq.

Eutrophication 4.3 8.01 kg PO₄ eq

Ecotoxicity 4.3 178000 m³ toxicity

Photochemical ozone creation 3.8 32.2 kg ethene eq.

Mineral extraction 3.5 5.04 tonnes

Human toxicity to water 2.6 0.0275 kg toxicity

% may not add up to 100% due to rounding

So for example, to calculate the Ecopoints for 1 tonne of mineral extraction:

Characterized impact = 1 tonne mineral extraction

Characterized impact for 1 typical UK citizen = 5.04 tonnes mineral extraction Normalized impact = 1 divided by 5.04 = 0.198

Weighting = 3.5%

Ecopoints = 0.198 multipled by 3.5 = 0.693 Ecopoints 2.6.3.3 EMBODIEDENERGY

As materials can be extracted in any part of the world and either processed into building components locally or transported as raw materials, it is virtually impossible to examine all of the possible environmental impacts that the various activities are likely to have because the variables are just so great.

Perhaps the only constant method there may be in the winning and working of materials, their transportation and processing into building components up to the point when they are assembled into completed buildings is the energy requirements of the various processes. The actual monetary value of energy can also be different from country to country, therefore it is not possible to use monetary value of energy as a unit of measure. However, the unit of energy input itself can be used.

As energy is required to be consumed at every stage of the production process, from extraction of the raw material to its incorporation into a construction, and eventually to demolition and possible reprocessing, the sum total of these energy inputs can be termed as the embodied energy of that product. It should therefore be scientifically possible to establish a method of calculating the quantity of embodied energy that is required to make a building component, be it a cubic metre of concrete, a single brick, a square metre of glass or a sheet of plasterboard.

Appendix A shows a comparison of embodied energy values for some common materials. From this it can be appreciated just how energy intensive some processes are and therefore how relatively good and bad some components are. If materials have to be imported or are chosen to be imported on the grounds of economic cost these will, by definition, carry a larger embodied energy by virtue of the cost of global transportation. Conversely, economies may be derived by local energy consumption and waste disposal which can also be incorporated into the equation.

Embodied energy impacts associated with materials have also been assessed quantitively by the BRE using Envest (see 2.6.3.2) which can also take account of the building form and fabric typical replacement intervals and other data held by the Centre for Sustainable Construction. The results generated are quoted in Ecopoints per m² of element and factors such as replacement intervals can also be factored in as part of a full cost and use study.

A fundamental difference in environmental terms between refurbishment and redevelopment is the saving of embodied environmental impact and energy if refurbishment is undertaken in preference to demolition and redevelopment.

PART 2, SECTION 6

The Surveyors’ Construction Handbook Part 2, Section 6 (revised 10/01) Effective from 1/12/01 Page 7

2.6.3.4 LEGISLATIVECHANGES

Armed with bench-marking data it would be possible for systems of regulation to be built into the existing regulations. With the increasing emphasis on energy conservation within the building regulations (which currently concentrate on energy consumed in use) it would be a simple extension of these regulations to lay down embodied energy maxima per square metre for various building types.

A major criticism that could be levelled at such a system is that it would starve the construction industry of design flexibility. However, this could be overcome by introducing a scale of energy taxation. This would enable those that wish to exceed the design criteria of the regulations to do so, but they would have to pay for the privilege. Conversely, those who produce buildings and achieve significant savings beneath the bench mark could receive aid in the form of grants as recognition for their efforts and ingenuity.