The aim of the Lifecycle Database is a free online information hub containing all of the environmental and design data necessary to specify timber as a first choice material.

In particular, it will focus on providing generic LCA datasets for key timber products used in the UK.

PE INTERNATIONAL has been engaged to oversee the collection, analysis and review of existing life cycle assessment (LCA) data for a wide range of timber and timber products. The company has extensive experience in the construction materials sector and in working with the timber industry, having previously completed a major LCA project on U.S. hardwood lumber for the American Hardwood Export Council (AHEC). These data will be used to generate generic LCA datasets for key timber products used in the UK.

The project is a result of on-going consultation with timber industry organisations and external stakeholders, including contractors’ groups, architects, professional institutions and many others.

All stakeholders will be able to access whole-life information on timber products free of charge through a dedicated website, managed by Wood for Good. Individual timber companies will be able to use these data as a basis for developing specific environmental product declarations (EPD) for their products.

The online hub at the core of the project will provide a user-friendly portal for information on carbon accounting and life cycle assessment (LCA) for timber.

The Lifecycle Database hub will incorporate both generic LCA datasets for the primary products developed during this project and existing manufacturer-specific datasets identified during a literature review, together with the related evidence base. Over time, it will also provide tools to allow manufacturers to produce their own Environmental Product Declarations (EPD).

The environmental data provided for the primary timber products are intended to be used at the building or end-use-product level, allowing comparisons to be made between different options, taking account of the full life cycle. Data for products themselves can only be compared where the full functionality through the life cycle has been considered.

This project focuses on timber and timber products produced and used in the UK, and will provide data for manufacturing and end of life. These timber products, such as kiln dried timber, wood panel products or engineered timber, are themselves the raw or primary materials used in buildings or other end-use products such as furniture; they are rarely an end-use product in themselves.

The products to be studied include:

A. Sawn Timber (produced and consumed in the UK)

B. Panel Products (all UK consumed)

C. Engineered Timber (all UK consumed)

D. Proprietary Products (all UK consumed)

All products, not just construction products, have an impact on the environment.

A construction product can have environmental impacts from the extraction of raw materials, their processing and manufacture, packaging and delivery to site, installation, maintenance and refurbishment and eventual recycling or disposal. This sequence of stages is known as the life cycle of the product. Calculation of the environmental impact of a product at all stages of the life cycle is called Life Cycle Assessment (LCA). LCA should report on all the significant environmental impacts associated with a product or process by considering a broad range of environmental issues.

The scope of LCAs can vary, but the manufacturing stage of the construction product will always be included; this is known as a ‘cradle to gate’ assessment. Some LCAs will also take into account transport of the product to the construction site and its installation; this is a ‘cradle through construction’ assessment. LCAs that also include the impacts of maintenance, refurbishment and eventual recycling or disposal are termed ‘cradle to grave’ assessments.

There are two types of traditional construction product LCA. Industry Average assessments use data from several manufacturers of the same type of product to create an industry average LCA for that product. Manufacturer Specific assessments use product-specific data provided by a single manufacturer, and apply only to the specified products.

LCAs should comply with ISO 14040:2006 [1] and ISO 14044:2006 [2] and a peer review is often undertaken to confirm this. Any LCA that is intended for publication and that compares products must be critically reviewed by a panel of independent experts to ensure that the relevant standards have been adhered to and that the assessment is robust (this is a requirement of the ISO standards).

A particular type of LCA study is an Environmental Product Declaration or EPD.

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[1] ISO 14040:2006 Environmental Management – Life Cycle Assessment – Principles and Framework

[2] ISO 14044:2006 Environmental Management – Life Cycle Assessment – Requirements and Guidelines

Environmental product declarations are standardised documents used to communicate the environmental performance of a particular product based on LCA.

EPD in general are covered by the ISO 14025:2006 standard, although the construction industry has also developed ISO 21930:2007 [1] and EN 15804:2012 to define how construction products should be assessed and reported using EPD. EN 15804:2012 [2] sets out how LCA should be used to consistently determine the environmental impacts associated with a construction product, generating results in a common format to enable building level assessment and comparison across Europe. Many hundreds of EPD are freely available from a number of European schemes and cover a very wide range of construction products, with most being for specific manufacturer’s products, although trade association EPD are also available. EPD schemes aligning to EN 15804:2012 include BRE’s new EN 15804 EPD Verification scheme [3] within the UK, FDES using the French Standard, NF P01-010 presented in the Inies database [4] in France, IBU in Germany and EPD Norge [4] in Norway.

All EPD are manufacturer declared data but should have been independently verified by an expert in LCA and the construction product itself before publication.

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[1] ISO 21930:2007 Sustainability in building construction – Environmental declaration of building products

[2] EN 15804:2012 Sustainability of construction works – Environmental product declarations – Core rules for the product category of construction products

[3] http://www.greenbooklive.com/search/scheme.jsp?id=260

[4] http://www.inies.fr/IniesConsultation.aspx

When trees and plants grow they take carbon from the atmosphere and incorporate it in molecules such as cellulose and carbohydrates.

This “biogenic” or “sequestered” carbon removes carbon dioxidefrom the atmosphere and has benefits, particularly for long life products such as construction materials, as the carbon stays “stored” in the product until disposal. However, disposal processes may release the carbon back into the atmosphere, either as carbon dioxide from combustion or aerobic decomposition processes, or as both carbon dioxide and methane from anaerobic decomposition.

A forest contains carbon not just in the living trees you can see above the ground, but in litter on the forest floor, and below ground in roots and soil.

These carbon stores, known as “carbon pools”, are shown in the figure below and include both living biomass and dead organic matter. Over time, the various parts of the forest can both emit carbon and remove carbon from the atmosphere. For example, as a tree grows, it creates new branches and roots which require carbon removal and sequestration within the tree. When leaves fall to the ground however, they decay causing emissions of carbon dioxide and methane. The overall balance of emissions and removals will result in an increase in carbon in the forest (a carbon sink), or a decrease in carbon in the forest (a net emission).

Quantifying these emissions and removals to calculate the balance requires an understanding of how natural processes and human actions interact.

The main greenhouse gas involved in forestry is carbon dioxide (CO2) from carbon stock changes. Other greenhouse gases often associated with agriculture include nitrous oxide (N2O) from, for example, nitrogen inputs (although applying fertiliser to forest land is not common practice in the UK), and methane (CH4) which is involved in the greenhouse gas balances of forests growing on highly organic soils such as peatlands.

Human management of forests can have a strong influence on the pattern of emissions and removals but managed forests are always susceptible to natural disturbances such as forest fires or storms which can lead to substantial release of carbon to the atmosphere or reduced sequestration from the atmosphere.

Understanding forest carbon balances as stock changes

The range of carbon pools involved in forest greenhouse gas balances and the types of issues raised in the preceding discussion can lead to the impression that forest greenhouse gas balances are difficult to understand and quantify. However, for most purposes forest carbon or greenhouse gas balances can be understood and modelled more simply by considering changes in carbon stocks.

The chart below shows how carbon stocks would change if a Scottish field were planted with Sitka Spruce. Before the trees are established the existing vegetation carbon stocks might typically comprise no more than 20 tonnes carbon per hectare (tC ha-1). The small initial loss of carbon stocks due to removal of existing vegetation is not shown in this chart. The land is assumed to be managed without any harvesting (either through thinning or clearfelling), effectively being allowed to develop into a ‘wilderness forest’.

The IPCC Guidelines were developed for the purpose of producing national greenhouse gas inventories rather than for considering sequestration or emissions associated with particular products. Hence this perspective is different to that of life cycle based greenhouse gas accounting methods.

Wood harvested from forest land, cropland and other types of land use will remain in products for differing lengths of time. Harvested Wood Products includes all wood material (including bark) that leaves harvest sites and constitutes a carbon reservoir. The time carbon is held in products varies depending on the product and its uses. For example, fuelwood and mill residue may be burned in the year of harvest; many types of paper are likely to have a use life of less than 5 years which may include recycling of paper; and sawnwood or panels used in buildings may be held for decades to over 100 years. Discarded Harvested Wood Products can be deposited in solid waste disposal sites where they may persist for long periods of time. Due to this storage in products in use and in solid waste disposal sites, the CO2 emissions from harvested wood products in a given year could be less, or potentially more, than the total amount of wood harvested in that year. Worldwide the amount of carbon held in harvested wood products is likely to be increasing.

Given that inputs do not in general equal outputs and that carbon can remain stored in Harvested Wood Products for extended periods of time, this storage time needs to be taken into account when providing guidelines for estimating the contribution of Harvested Wood Products to carbon dioxide emissions/removals associated with agriculture, forestry and other land use projects.

The following data are required for calculating greenhouse gas withdrawals and emissions at the national level:

• Annual change in carbon stock in Harvested Wood Products in the reporting country, including Harvested Wood Products stocks from both domestic harvest and imports

• Annual change in carbon stock in Harvested Wood Products made from wood harvested in the reporting country including annual change in carbon stock in Harvested Wood Products exported to other countries

• Annual imports of all types of wood and paper material to the reporting country

• Annual exports of all types of wood and paper material from the reporting country

• Annual harvest for wood products in the reporting country.

Regulatory and legislative frameworks for construction and manufacturing are becoming ever more restrictive.

As such, in future it is expected that assessment of environmental impacts will be increasingly important customer drivers alongside cost and performance criteria throughout the construction sector. This in turn means that there will be increasing demand from clients in the construction and manufacturing industries for robust, accessible data showing measurement and assessment of supply chains, performance of products in design, construction, whole-life assessment and end-of-life considerations among other factors.

Many other industries, including competing material sectors, recognise the importance of these changes and have taken the lead in promoting positive information to their target audience. The timber industry is determined to do the same. Without it, specifiers and buyers will choose the products and materials for which clear data exists and ignore those which cannot back up their claims.

PE’s approach to the generation of GHG and LCA data for the primary products to be assessed in the project (see above) is informed by similar work which they have undertaken to develop generic construction databases for Germany, Europe (as a region), Brazil, China, and Ukraine and generic national LCA databases for Malaysia and France.

This approach uses existing underlying data from LCA models, within the highly regarded GaBi Life Cycle Database, adapted to compensate for differences in a particular region by considering the particular mix of technology used and making use of relevant regional data for the most sensitive input/output variables to the model to provide “generic data” for the region.

This adaptive, or compensatory approach must be distinguished from a more conventional LCA based approach where all, or a selection of manufacturers supplying a region, provide complete data on their processes which are then modelled and averaged, to generate “average data” for the region.

Because “average data” will more accurately represent a typical product than “generic data” can, it should always be used in preference if available. There are also limitations to the claims that can be made for the representativeness of “generic data”. However, given the number and geography of suppliers to the UK market, the costs of data collection and modelling to generate “average data” for the number of products in the brief cannot be accommodated in the available project budget.

Although the work will be guided by the review of regulation and policy, the intention at this stage would be to provide a generic LCA database for timber and timber products aligning with the CEN/TC 350 standards, and which could be pre-verified according to CEN/TR 15941:2010 for use in building-level assessment to EN 15978, and for use as generic data for input materials in the preparation of EPDs to EN 15804 where specific data are not available. CEN/TR 15941:2010 is the CEN/TC 350 report covering generic data, which provides guidelines on the required quality of data, and gives provision for the pre-verification of generic data. Relevant text from the standard is presented below:

“CEN/TR 15941:2010 4.1

Generic data are used instead of system specific data to describe the environmental impacts and aspects of a product's life cycle in an LCA study. Generic data are used for calculations where system specific data LCI/LCA data are not available or where other non-system specific LCI or technical data are required”.

“CEN/TR 15941:2010 4.3.4 Compensating with generic data for differences in local conditions

Often generic data will not directly reflect the local conditions (i.e. the actual situation) under study. Data compensation then has to take place. Compensation on a quantitative empirical basis for local conditions is always the best option. This however presupposes the practitioner's detailed understanding of the information under the local conditions and therefore understanding the different measures to be taken for compensating any bias in the information. When informed compensation of the data is not possible, informed assumptions have to be made. These kinds of assumptions are common in LCA since often no other option is available. Such assumptions should always be reported in the LCA-report and the sensitivity of the analysis resulting from such assumptions should be evaluated.CEN/TR 15941:2010

The process described here allows for the provision for a single generic dataset for both production (based on a consumption-weighted average of species, technologies and imports/UK produced if relevant), and with typical UK end of life data for all the products listed in “What products are covered by Lifecycle Database?”