Kemi i byggeri
Summary and conclusions
Introduction
In various ways, initiatives are made to get a general idea of and limit the environmental impact of building activities. In Denmark, e.g. a LCA tool (BEAT) has been developed focussing on the consumption of raw materials and energy sources, a labelling system has been established regarding indoor climate and the building industry has built a chemicals database (Dansk Kemidatabase). Within the framework of the Nordic Ecolabel, draft criteria for single-family houses have been prepared focussing on energy, selection of materials, environment, indoor climate and waste.
This study comprises a survey and an assessment of the use of selected chemical substances, chemical products and materials in the different phases of the life cycle of a building, i.e. the construction/renovation phase, the operational phase and the demolition phase. The study is one of several projects initiated by the Danish EPA in 2002 with the purpose of strengthening the efforts in pursuit of less environmentally hazardous building activities.
As in other industries, the consumption of chemical substances, products and materials constantly changes within the building industry. New products with better technical properties are developed and undesirable hazardous chemicals are substituted. Many of the problematic substances previously used in building activities, e.g. PCB, lead, cadmium and mercury have been phased out today.
The objectives of this study were
- To establish an overview of the actual consumption within the building industry of chemical substances hazardous to health and the environment
- To develop an IT tool for assessment and prioritisation of chemicals used in the building industry with respect to their environmentally and health hazardous properties.
The consumption of chemical substances/products and selected building materials was mapped out quantitatively in cooperation with selected typical Skanska building sites (cases). The survey included registration of prioritised products and materials for the involved building sites throughout the entire construction time stretching over 6-11 months from April 2003 to March 2004. One of the building activities (Care Centre Grønnehaven) was, however, not finalized until after the termination of the mapping phase of this study and, consequently, the survey was partly based on the expected consumption.
Mapping surveys
The accomplished survey was based on information from the following types of building activities:
- Industrial/commercial buildings (Sundby Crematorium on Amager)
- Sensitive buildings (Care Centre Grønnehaven, old people’s housing in Elsinore)
- Housing, new-built (Øresund Strandpark [the Sound Marina Park], 61 owner-occupied flats on Amager)
Industrial/commercial buildings differ from house buildings in that they typically contain less square metres of kitchen and toilet facilities and a larger area with large rooms, e.g. store rooms, meeting rooms, special-purpose rooms, etc. These differences have an influence on the consumption of materials and products during the construction of the building. Sensitive buildings (e.g. kindergartens, old people’s housing, a.o.) may differ from ordinary house buildings in that they have special facilities, e.g. lifts and special-purpose kitchens and in that the selection of e.g. products and materials not harmful to the indoor climate is brought into focus.
Results of the survey
A total of 79 different chemical products and 31 materials were registered. The chemical products include: glues and adhesives; joint fillers; paints and the like; concrete - plaster and mortar; lubricants; cutting oil and slip agents together with a number of other product types including asphalt, foam and bottled gas. The materials comprise: metal roofs and metal gutters; roofing felt and building paper; covering materials and vapour barriers; insulating materials; wall lining; plastic pipes; steel pipes; built-in boxes and electric outlets; linoleum floors and pressure-creosoted wood (Chapter 2).
Information on the ingredients of the chemical products was gathered from their mandatory safety data sheets and as for the materials primarily by contacting the suppliers but also by examining existing assessments of similar materials. The amounts consumed of the individual products and materials together with information on the ingredients and their classification according to hazard are accumulated in the IT tool, BYG-IT (an Access database), which was developed within the framework of this project. The survey showed that, in the chemical products, the substances butane oxyime and diphenyl methane diiosocyanate were found. Both substances are entered on the Danish EPA list of undesirable substances (LOUS). In the registered materials, 16 substances or groups of substances occurring on the LOUS were identified, including copper, boric acid and PAHs. It should, however, be noted that, for more of these substances, no certain documentation was available, proving that the substances were actually present in the specific materials used. Furthermore, a number of other potentially health and/or environmentally problematic substances were registered in either the chemical products or in the materials, e.g. the allergenic substances 2-hydroxy propyl methacrylate, cobalt thallate and dibenoyl peroxide and the fungicide tebuconazole in pressure-treated wood. Tebuconazole is under suspicion of being carcinogenic and is very toxic to aquatic organisms.
Development of IT tool
The aim of the second part of the project - the development of an IT tool for assessment and prioritisation of chemicals used in the building industry - was to equip the builders and contractors with a simple tool giving a quantitative measure of the health and environmental impact of a building activity (Chapter 3). The tool was limited to include three of the five life-cycle phases of a building, i.e. construction/renovation (being built), operation (use of the building) and demolition. Furthermore, the health assessments only comprise the phases in which the individual products used are detectable, i.e. the construction/renovation phase and the operational phase. The demolition phase is thus not included in the health assessment as the individual substances and products are hard to trace in this phase and as other health nuisances, dust for instance, are considered more serious than exposure to chemicals.
Structure and fields of application of the IT-tool
The focus areas of the prioritisation model are outlined in the figure below.
For each of the life-cycle phases of the building, the impact (or risk of health or environmental effects) is estimated as a product of the exposure of humans (health) and the environment and the hazard of the individual chemicals/substances:
Impact (risk) = Exposure × hazard
The exposure part of the model comprises two methods:
- A simplified method based solely on the consumed amount of substance/product and on its application.
- A more detailed method based on simple scenarios reflecting the health and environmental exposure in various situations, e.g. in working environment, indoor climate and spillage to soil.
The first method requires only few data and may be used for a quick rough screening of the potential exposure to a product. The other more detailed method distinguishes substances released to the environment from substances remaining in the building materials. The latter method thus gives a more true evaluation of the exposure.
In the health part of the model, the extent of the exposure is given as a relative score while the score for exposure to a chemical in the working environment is calculated as a product of the following factors:
Score for exposure in the working environment = Score for consumption × score for application
For indoor climate, the score for exposure is calculated on the basis of the score for consumption and type of building:
Score for indoor climate exposure = Score for consumption × score for type of building
The health part of the model makes it possible to rank the products within a product group but not to estimate exposure concentrations. Such estimations require very extensive calculation tools and considerably more data than those typically appearing from the mandatory safety data sheets.
Contrary to the health part, the exposure model for the environmental part (the detailed method) makes it possible to estimate concentrations of substances in various parts of the environment, i.e. soil, water, air and waste for each of the three life-cycle phases. Furthermore, the model makes it possible to state whether a chemical is released via sewer or directly to an aqueous recipient. If the chemical is discharged via sewer, the elimination of substance in the wastewater treatment plant is assessed. In the simplified method based on a slender data basis, the whole amount consumed of a chemical is considered to be released to surface water.
The prioritisation model assessment of the hazard of the chemical substances and products is based on a method developed in collaboration between DHI and DTC in Centre for Chemicals in Industrial Production (KEMI). The method operates with a score for environmental hazard and a score for health hazard, which is often further grouped into two scores: a score for inhalation and a score for contact with skin. The environmental and health hazards are assessed on a scale from 1 to 5, of which 5 is most hazardous.
The chemicals consumption of a building activity will among other things depend on the size of the building (m² of built area, ground area etc.) and on the type of building (industrial/commercial, habitation, sensitive etc.). A number of applicable normalisation factors are incorporated in the prioritisation tool. In the calculations made for the three building site cases, the impact is estimated per m² floorage.
The prioritisation model is incorporated in the BYT-IT database developed, which also includes the data on the survey part of this study. The tool may be downloaded from the Danish EPA web site (www.mst.dk). The BYG-IT users may enter new buildings, chemicals etc. Appendix L of this report gives a description of the tool structure and user directions.
Results from use of the IT tool
The use of the prioritisation model is illustrated through a thorough review of the assessment of a waterproofing used during the building of Care Centre Grønnehaven (Chapter 4). The process starts with registration of amounts used and product data from the safety data sheet followed by a calculation of its impact on health and the environment as illustrated in the figure below, which shows the general principles of the steps of the model.
The potential health effects were calculated for all 76 registered building products, which were grouped into 21 products types by use of the prioritisation model. The results are given as the health impact in case of contact with skin for the working environment, inhalation for the working environment and indoor climate in the operational phase. For the Sundby Crematorium building, the model showed that a PUR sealant product was expected to be the relatively largest contributor to the health impact via inhalation. This and other results of the health assessment are, however, not altogether reliable as the model used primarily is applicable for comparison of products with the same technical function.
With only few resources, the health prioritisation model may be used for eliminating the most health hazardous products by comparing more products within the same category. The model cannot, however, be used for quantitative comparison of products from different product categories or for comparison of impact caused by contact with skin to impact caused by inhalation.
The environmental part of the prioritisation model is used for calculating the environmental impact of chemicals and products at two levels:
- Substance level taking into account the hazard, emission and redistribution in the environment of the individual substances
- Product level based on the hazard, emission and redistribution in the environment of the whole product. This method is applicable when no detailed information is available on the composition of the product
Furthermore, the exposure is calculated both with the simple screening model for exposure (consumption of substance/product) and with the more detailed model based on simple scenarios for the application areas of the substances/products.
The results of the calculations of the environmental impact for the three building site cases indicate that, in some cases, the simple exposure model does not give a quite true picture. For the Care Centre Grønnehaven, the two calculations models resulted in e.g. different prioritisation orders (i.e. extent of potential environmental impact) for the same products while, for the Sundby Crematorium, the prioritisation order was unaffected by the calculation model used.
The current three building site cases showed that while the demolition phase only contributed a little to the total environmental impact, the construction and operational phases contributed with the same order of magnitude. It was assumed that the lifetimes of the chemicals and the building are identical, which will not always be the case for all chemicals. Furthermore, the three site cases showed that asphalt, waterproofing and the material zinc gutters were some of the product types contributing most to the environmental impact.
Recommendations
It is recommended that the health and environmental impact model is used as a prioritisation tool in the planning process of new buildings and renovation of existing buildings (Chapter 5). Furthermore, it is recommended that the developed IT tool is used for documenting the requirements made to the chemical building products in relation to the new Swan eco-label for standard single-family houses.
Furthermore, it is recommended that the tool is further developed to include all five life-cycle phases of a building and that it is linked to other existing tools within the building industry, e.g. the Danish Building Research Institute, SBi’s LCA tool BEAT and the building industry’s chemicals database Dansk Kemidatabase.
Version 1.0 Januar 2007, © Miljøstyrelsen.