It is sometimes possible to save money in the future by making optimally informed choices as to the best allocation of scarce resources. When procuring a built asset, WLC assumes that specification of building components must consider the both the initial capital cost, operational costs and also disposal costs at the end of a products life cycle. This suggests it may be necessary to spend more money in the initial construction phase in order to benefit from lower operating cost during the life time (although this is not always the case).

Definition of WLC

Whole life costing (WLC) is defined in the ISO Standard 15686 on Service Life Planning as follows:

"Whole life costing is a tool to assist in assessing the cost performance of construction work, aimed at facilitating choices where there are alternative means of achieving the client's objectives and where those alternatives differ, not only in their initial costs but also in their subsequent operational costs"

Or

"The systematic consideration of all relevant costs and revenues associated with the acquisition of an asset" (CRISP definition).

What is WLC?

WLC is the estimation of the monetary costs for the construction, operation, maintenance and repair (and sometimes demolition) of a built asset over a chosen study period. The purpose of a WLC model is to improve the decisions being made by practitioners. Forecasts may be used to improve design, specification and through life maintenance and operation of an asset which will have various economic benefits. It may be applied to either new designs or to existing structures, enabling residual life and value to be estimated. As various activities take place at different times to maintain the asset the incremental costs have to be converted to present day value using a discounted cash flow technique. WLC relies on predicting when elements of the asset will deteriorate to a condition at which intervention is needed and what the discounted cost will be for each activity.

Using WLCcomparator to calculate the WLC

WLCcomparator is a tool that has been designed to calculate the WLC of Building components and elements.

WLCcomparator provides a platform to assess the basic criteria for capital investments in an effort to ensure a reduction of future operating costs. The analytical approach enables Whole Life Costing to be performed at building component and element level. The model captures the economic analysis needed to improve capital investment decision, optimise asset selection or design, and predict the best combination of interdependent systems.

The model adopts HM Treasury complaint standard and accepted accountancy rules for predicting the present value of future income streams. The approach also supports the new ISO 15686.

This model has been used to assess the WLC implications of procuring FRP building products against substitutes made from other materials, and also compare the cost implications of the various methods that can be adopted to dispose of the products.

The Procedure adopted for calculating WLC

WLC formula

The purpose of a WLC study is to forecast the cost of maintaining and operating, and disposal of the above mentioned properties, and includes the cost of capital, installation and replacement of component parts. The initial costs are capital and labour cost required necessary to purchase and install a product. The operational costs are the replacement costs, installation and disposal costs incurred during the chosen study period.
This information has been used to calculate the WLC adopting the formula:

Equation 1 - WLC equation (Adapted from Lee 1998)

Financial criteria

The WLC analysis requires that year on year cash are discounted to reflect the time value of money. A discount rate of 6% has been applied in the study. This reflects the cost to taxpayers of a phased grant or loan.
The following formula has been used

Equation 2 - Discount equation to allow for the time value of money (Treasury 1997)

The year on year cash flows (periodic money streams that are expected to continue in the future) are discounted to account for the fact that these monies will be worth less in the future than they are today. When the monies are discounted they are expressed as present values (PVs).

In order to compute present values, it is necessary to discount future costs (and benefits). Discounting reflects the time value of money. As a result of discounting benefits and costs are worth more if they are experienced sooner. The higher the discount rate, the lower is the present value of future cash flows.

More information is available on this in the "Green Book" (Treasury 1997), Appraisal and Evaluation in Central Government, HM Treasury.

Capital replacements

If the service life of an element is less than the WLC study period a replacement of this item is necessary. The model will assumes planned replacements of component parts when the life expectancy is less than the WLC study period.

Disposal of products

The removal of a component will incur cost. The WLC model will include an expected cost to deconstruct the component by various means. To calculate this cost it is necessary identify the resources that will be needed to deconstruct a component. The cost will be for the purchase or hire of capital, labour and overhead to deconstruct a component. The procedure for calculating the cost of deconstruction of a component can be expressed as: When a product is to be replaced there is the possibility for the obsolete product to be disposed of it will incur a cost, and may also earn an income depending on the chosen disposal method.

Equation 3 - Disposal cost equation

To dispose of a component will incur a cost. For example if the product is intended to be sent to landfill there will be a cost associated with the hire of a skip, transportation to landfill and also the cost of disposing material as landfill. Similarly if a product is intended to be recycled similar charge for skip hire, and transportation would apply.

The component that has just been allocated a disposal cost (DCa) may be able to earn an income if it is sold, and is said to have a residual value (Ra). For example recycling or re-use.

Equation 4 - Disposal Value equation

Assets may or may not have a positive Disposal Value when the residual value and disposal costs are included in the calculation.

The purpose of the model is to allow various deconstruction options of FRP to be assessed and entered into the WLC model to evaluate assess the cost effectiveness of recycling FRP products.

The income earned in recycling will be based on the market value. This represents the most probable price that should result under specific market conditions. The market comprises of available buyers and sellers for an exchange. The market value for the disposal of an asset is dependent on the market for the asset under consideration and the perceived advantages it offers the buyers in that market. An asset can have a range of values to potential buyers, with each valuing different aspects of the asset. Similarly number of sellers in the market will also have an influence on the market price.

Special considerations when calculating the WLC of FRP building products

The nature of FRP products are often bespoke designs and functionally specific requirements. This may limit the scope for re-use of FRP products.

FRP products are durable products and are likely to have a long design life when compared to substitute goods. However, replacement of the product may not be due to technical obsolescence (advances in technology and the creation of more efficient products) or physical obsolescence (deterioration beyond normal repair) but due to:

• aesthetic obsolescence such as changes in architecture that make components and buildings no longer fashionable.
• legal obsolescence due to changes in legislation prohibiting the use of materials and products that fail to meet regulations
• functional obsolescence due technological developments that has meant the original purpose of the product is no longer required
• social obsolescence where by changes in the needs of society means they longer require the product

Bespoke products may have bespoke fixtures and fittings that are costly (both labour and tools) to remove before disposal.

FRP products have a high energy value (around 36 MJ/kg). Although the primary business of a waste incinerator is waste disposal, energy production is a by-product. Processing FRP into a fuel to be burnt directly instead of oil or coal in a PowerStation may be a viable way of earning an income from obsolete FRP building products.

FRP products are often lightweight when compared to substitute goods made from alternative materials

FRP products can be coloured. This may be desirable when procuring some building products in designing a built asset with aesthetic value. Note that colouring FRPs may increase the rate of technical obsolescence if it is subject to discoloration

FRP products are corrosion resistant. The maintenance regime and operating costs as a result maybe less than for substitute goods

WLC of FRP Bridges

Ehlen (1996) reports that FRP are technically viable substitutes for conventional bridge materials. It states that there is a financial barrier, given their higher initial capital cost, regardless of the potential life cycle cost savings (or reductions in the WLC) that may be achieved. The report provides a method for evaluating the WLC / (or life cycle cost as referred to in the publication) effectiveness of new materials in comparison to traditional ones. This methodology is consistent with the identified and applied methodology made to make in the WLC study of the doors and windows.

Ehlen (1996) identifies the lcc formula to be:

and this is the same as the approach used in the BRE WLCcomparator.

Ehlen goes into some detail comparing the initial construction cost, operating costs, maintenance costs and repair costs (OM and R), and presents the findings in tabular and graphical analysis, which has been summarised in pie charts, as shown in figure 2.

The report then goes on to analysis which of the components are most sensitive to variations in cost and duration of operation, maintenance, and repair activities. It concludes that the most significant cost items are price variability of material costs and length of road works. The potential benefits of FRP bridge designs seem to be that repair time, disposal item, accident costs, installation time, driver delay time are all lower than for the concrete alternative.

Ehlen (1996) also states that it is likely that FRP materials could be technical and economic substitutes for use in marine structures, and offshore oil rigs.

The report concludes that it expects the initial construction costs to reduce once new technologies become more commonly applied and accepted, making it more cost competitive with traditional ones. That there are certain cost advantages (as identified above).

The report contains detailed breakdown of the life cycle cost (LCC - same as whole life costs) analysis and can be downloaded at http://fire.nist.gov/bfrlpubs/build96/art115.html

Ehlen (1997) states the FRP materials are often specified because they have some qualitative performance advantage over a conventional material. For example FRP composites give designers the flexibility to create unique and light structural shapes which can be installed by hand instead of by crane. This report summarises much of what was written by Ehlen and Marshall in 1996.

The case study compares the WLC / LCC costs for various composite bridge designs the reinforced concrete deck structure. The analysis concludes that whilst the FRP composite deck has a higher construction cost (325 000 rather than 225 000 ) its disposal costs are less, 12000 versus 75 000 of the concrete given it can be disposed of quickly and by hand labour. The FRP OM and R costs are higher, and this was attributed to the costs of introducing a new technology. It is claimed that these are likely to reduce and make the FRP products more cost competitive on a WLC basis.

The report contains detailed breakdown of the analysis and can be downloaded at http://fire.nist.gov/bfrlpubs/build97/art085.html

Kumar (2001) presents a paper to demonstrate the fatigue and strength experimental. qualifications performed for an all-composite bridge deck. This bridge deck, made up of FRP was installed on the campus at University of Missouri at Rolla on July 29th, 2000. The materials used for the fabrication of this 9.14 m (30 ft) long by 2.74 m (9 ft) wide deck were 76 mm (3 in) pultruded square hollow glass and carbon FRP tubes of varying lengths, bonded using an epoxy adhesive and mechanically fastened together. The cross-section of the deck was in the form of four identical I-beams running along the length of the bridge. Fatigue and failure tests were conducted on a 9.14 m (30 ft) long by 610 mm (2 ft) wide prototype deck sample, equivalent to a quarter portion of the bridge deck. The report states FRP are being used in infrastructure as alternative to conventional materials. The report points to evidence of increased stiffness and strength-to-weight ratios, excellent fatigue and corrosion resistance, faster installation time, and reduced maintenance costs for FRPs, as well as superior resistance to environmental degradation as compared to traditional building materials and claims that these characteristics of FRP lead to several cost-performance benefits when applied for transportation infrastructure applications.

Kumar also states that bridge decking appears to be one of the most promising applications for composites in infrastructure and states that it is a cost effective solution for the repair and replacement of concrete and steel in bridges.

The Innovative Bridge Research Program has been set up to encourage the construction of bridges that last longer and require less maintenance, so as to reduce traffic congestion and disruption resulting from bridge construction and rehabilitation projects.. A report written by Ruth W. Stidger, Editor-in-Chief states that the program also has the goal of reducing the maintenance and life-cycle costs of bridges, including the costs of new construction and the replacement or rehabilitation of deficient bridges.

Of the 157 bridge projects have been funded, and include the use of high-performance steel for the girders and steel plate of a bridge in California, the incorporation of fiber-reinforced polymers into the deck slab of a bridge in Iowa, and the use of high-performance concrete to build the deck slab of a Chicago, Illinois structure. Of the 157 projects funded between 1998 and 2001, 84 used fiber-reinforced polymers, 30 involved high-performance concrete, 24 incorporated alternate rebars such as corrosion-resistant steel and solid stainless steel, 17 used high-performance steel, and 20 incorporated a diverse range of other technologies (note: some projects used more than one material).

The high number that used FRP material seems to suggest they offer potential for cost savings during the life of the constructed asset.

Mouchel, a large UK based construction company who have designed and constructed the West Mill Bridge. The bridge was built using an FRP bridge deck, able carry 40 tonne vehicles. It was open to the public from 29th October 2002. The bridge deck weighing 38t (12t advanced composite, 26t concrete) was lifted into position on 8th October 2002. A WLC analysis has been carried out to asses the cost effectiveness of this design option. We have not made any conclusions from it, given we have not seen reviews of it in the public domain. However, it could be seen to be evidence of successful and cost effective design and construction of a bridge using FRP materials.

WLC of FRP Marine Piles

A literature review has found evidence of technical benefits of procuring FRP marine piles, although we were unable to find any evidence of cost savings and reduction of life cycle costs where they have been used. The literature review concludes that composite plastic/GRP reinforced piles can be used for marine applications such as quays, dolphins, jetties etc., as an alternative to driven timber, steel and reinforced concrete.

Emerging construction technologies have reviewed CP40, a round, vertical, structural element for use in corrosive outdoor environments. (http://www.newtechnologies.org/ECT/Civil/cp40.htm)

Lancashire Composite has focused it's resources on the successful design, development and commercial implementation of a marine piling that is economical, corrosion resistant, environmentally safe and readily available. The FRP Pile is commercially available as Composite Pile 40 (CP-40).

Further information on the benefits and technical aspects of the product are available at
http://www.lancastercomposite.com/

The benefit of strong, corrosion-resistant marine piling (8" to 24" outside diameter, and larger) are needed in waterfront infrastructure & structures such as locks/dams, canals, docks, piers, marinas, etc. Strong, corrosion-resistant fence and sign posts (2" to 4" outside diameter) are needed for facility/property perimeters and highway applications where groundwater, shorefront, de-icing, etc. conditions rust, rot, or corrode traditional materials.

It is claimed that CP40 has the strength required of traditional materials, but serves longer in harsh conditions such as those of the marine environment. CP40's advantages over traditional piling materials (wood, concrete, steel, aluminium) include:

• cannot rot, rust, or corrode
• not subject to marine borers and ship worm damage
• uniform piles available in any length, in any quantity
• easy to handle and drive
• electromagnetically invisible
• no hazmat
• low/no maintenance
• colour available
• greatly extended service life
• reliable design loads
• off-the-shelf product with established standard performance

Possible applications identified include:

• structural piles - piers, docks, wharves ,boardwalks
• fendering piles - fender piles, mooring piles, dolphin piles, approach walls
• foundations & other - foundation piles, columns, caissons, stay-on-place forms, navigational aids.

Identified barriers to its adoption include

• engineers are unfamiliar with the new material
• it often carries an initial price premium.

WLC for window profile

A study has been carried out by BRE to forecast the WLC of an FRP Window system, test for significant cost assumptions, and compare the WLC against a forecast of an assumed typical UPVC substitute product . The estimate has been produced using a best practice approach to WLC, accepted accounting principles and has relied on relevant data and information supplied by (or agreed with) the manufacturer.

The study includes sensitivity analysis to analyse how the WLC forecast would change if any assumptions made in the study were to change. The results of the sensitivity analysis concludes that the most significant assumption on the cost of input parameters is the initial capital cost, followed closely by cost of maintenance. From the maintenance tasks identified the most significant cost is cleaning exposed surfaces, followed by inspecting eases and trickle vents. The effect of a change in the duration between maintenance tasks most significantly effects inspecting eases and adjusting trickle vents, followed closely by lubricate and adjust hinges, ironmongery etc. The study period of this WLC analysis was is 30 years and the expected life expectancy of the FRP Window has been assumed to be 50 years. This has meant that variance in the service life of the product (plus or minus 10%) does not effect the WLC should this input parameter take on a different value.

An indicative WLC comparison between a UPVC window and the FRP window was carried out and concluded that the FRP product had a lower WLC over a 30 year study period (discounted at 6%). It was assumed that the UPVC window had a life expectancy of 15 years, and whilst required less maintenance the 1 replacement of the component at year 15 meant that the WLC was greater than the FRP window in this analysis.