Síntesis de composites de Poliuretano/Sílice (AEROSIL ® )

Was the strong cycle of the revival of these forms of contract in the 1990s a reaction to the perceptions of costly layers of management and client difficulties in achieving financial redress for performance failure?

Or was it lessons learned from the earlier D & B cycle that led to the present innovative enquiries?

D & B contracts place the greatest risk with the contractor, for he is responsible for the design. Nowhere is that risk greater than with building services. In the best organized D & B contractors the site manager may have lived from enquiry, through tender design up to contract award. If fortunate enough to have done so he will have acquired an understanding of the risks devolving from the tightness of the brief and selection of BS systems. Knowledge will have been gained of the strengths and weaknesses of ‘in house or brought in’ design services.

Analysis of current D & B enquiries shows that over 80% of them come with various elements of pre-design. These not only, but mainly, related to BS, come with conditions requiring confirmation that the numerical criteria of the brief will be met, particularly concerning the internal climate, noise and lighting.

Where BS systems have been selected in principle if not in detail, then the tenderer’s confirmation that their suitability and space allocation is accepted is sought quickly. A variant woven into this format is the request or invitation for the concept designs to be novated for development by the winning contractor. The contractor that markets in the D & B field without in house building services expertise is courting grave risk. If the site manager is assigned to the D & B project only at the time of award he would be wise to seek assurances that the BS criteria can be achieved by the selected building services systems. With time the greatest difficulty that the tendering services contractor has to surmount, designs are most likely to have been developed only in order to assess costs. These assessment/estimates are easier to calculate for the building elements than they are for the services. With short tendering periods very few services schemes are fully designed in the not untypical three-to six-week bid period. Appraisal of the employer’s requirements, development of team strategy, use of in house or external services consultant to customize the building services brief, leaves say two to four weeks for the M & E contractor, who will go through the same appraisal. On a multi-service enquiry, documents will be copied to the four corners of the office—mechanical, electrical, public health and fire (e.g. sprinklers). Calculations to determine number and size of major plant and equipment are prepared for boilers, chillers, generators, switchboards, water storage tanks, pumps and calorifiers, etc.

Telephone enquiries will bring a mix of budget/standard item prices.

Schemes will be laid out (sort the coordination clashes out later), the quantities taken off and fittings (bends, tees, junction boxes, etc.) are included in the ‘run’. Is there time to get prices in for the sublets (ducting, insulation, controls—building management systems (BMS), fire detection and security)? What about the contractor’s request to put forward alternatives? What about displacement ventilation and chilled ceilings? Okay, do it on a cost per square metre?

The chief estimator receives four BS estimates containing varying degrees of risk. The tender meeting is 5.00 p.m. today. The D & B contractor receives a fax of the BS tender form with a single lump sum, but no supporting breakdown. A flurry of faxes provides the breakdown.

A quick comparison across the computerized shreadsheet shows up the tenderer’s highs and lows. Explanation is sought by fax and phone. The lowest services price is included with the second lowest alternative. ‘We still haven’t got the running costs or sample of maintenance contract?’

Hey! I’ve just discovered the lowest alternative we’ve included requires us to put in double glazing with low emissivity glass—what’s that?’

Somehow it all comes together and is remarkably well presented. The interview goes well, your services manager was well prepared. You have got the job, but it’s riddled with risk, has to be designed properly, and starts on site in four weeks time. ‘Where’s the drainage layout?’ ‘Don’t forget the earth rod pits!’ ‘Can’t they bring the gas main in at the weekend? Otherwise I’ll be without site access for twenty-four hours’.

Enough author’s self indulgence, let us return to sanity and consider design, manage and construct. This is a single point responsibility but one in which the client usually involves himself in the contractor’s appointment of designers and package contractors. These may be reduced in number, packaging the work under a number of prime contracts. It is usual for the construction cash flow to remain with the contractor with design fees paid by the client. The contractor will control his managing staffing levels. Profit will be the fee. This is perhaps, the most suitable contractual arrangement for giving a client a guaranteed maximum price (GMP). The contractor may not know the moment when the client is going to ask for the contract to be converted into a GMP. The response must be very carefully considered. If earlier in the contract the risk from the BS angle is less. Before responding the design can be audited and reassurance sought that it will perform as required. A GMP requested once commissioning of BS has commenced is of quite different order. Time is short and the client impatient at the delay while a belated design audit is carried out. Meanwhile commissioning is progressing apace and may be showing up some problems. At the beginning of the job the contractor has all the contract value to spend and can buy in performance assurance and include it in the GMP. At the end of the project with most of the value expended and perhaps only 10% of the project value to come, the contractor has

The impact of the chosen contractual route 49

50 Risk and its mitigation

difficulty in asking for a further 10% to cover the risk of services failing in some aspect or other. The site manager who has stayed closely involved with engineering services has an important part to play in discussions with the contracts manager/commercial director in capping the contract value.

2.3.6 SUMMARY

In ascending order, risks arising from the BS element and the chosen contractual routes are summarized as:

• Traditional including those newly derived from the national engineering contract (NEC): lowest risk if fully designed and installed by a well procured subcontractor. Rising in risk according to the amount of undesigned Provisional Sums and Prime Cost items.

• Traditional with contractor’s design portions: risk arising where the services elements form part of the design portion, or interface with other design portions such as cladding. In this instance difficulties have been known to occur with fixings for perimeter heating, HVAC equipment and permissible levels of air leakage.

• Management contracting: incompatible packaging of work giving rise to difficult subcontract management.

• Construction management: as for management contracting plus greater risk due to the monitoring-only role of the construction manager of the on-site works. To a degree this is compensated for by a better quality of input to the design appraisal, constructability and commissionability of the building services.

• Design and build: clients see this as the route with least risk. The D &

B contractor sees it as a business of higher risk with commensurate reward. A number of D & B contractors provide an excellent product, but many have a common weakness and expose themselves to unnecessary risk through an inadequate comprehension of building services. This risk manifests itself in a number of ways—the lack of in house building services expertise, and the employment of cheap, lower division, underresourced consultants with narrow experience. Others without design expertise, and recognizing the pressures of tendering time, go to D & B BS contractors. Regrettably many previously excellent BS firms have been forced to disband their design departments or operate a shell, buying back agency staff on an as needed basis. A glossy presentation behind a subeconomic price can, by its attractiveness, deter an unsuspecting client from probing the disguise into clutching the single point responsibility. After all, this principle with speed, low cost and acceptable quality was the reason for the D & B route.

Project management does not feature in the above contractual order of risk, being a method for managing a project for which selection of the building contract route is but one function. Despite finding the addition of another layer of management irksome the building site manager is to be encouraged to find out how satisfied the PM is with the building services design. Questions along the following lines should be asked:

• Is this proven technology?

• Are there any aspects that make it difficult on this project?

• What is innovative about it?

• Have the innovative features been tested?

• Were the results satisfactory?

• Can we have copies of the reports?

• What aspects of design most concern you?

The best PM will be happy to inform the building site manager.

The site manager is reminded that this is the expected order of risk arising from building services under the contractual arrangements he may experience. There is little the site manager can do to mitigate the impact of the chosen route if the site manager is not part of that process of choice. Frustrating though it is to be embroiled in difficulties not of your own making there is much that can be done to assess areas of known and unknown but potential risk. Fore-armed with this knowledge the site manager will be able to make a contribution to the resolution of difficulties and remain in control of his site. Without this knowledge of contractual route risk the site manager will become no more than the figurative head as the project becomes swamped with the opinions of conflicting expertise talking an alien language.

2.4.1 GENERAL

The technical risk of BS is more easily understood from a platform of basic knowledge. The most basic framework is provided in Chapter 1.

Variously site managers will acquire deeper knowledge through training, including CPD, and will be able to flesh out the framework with their understanding of specific types of systems. All those who attain the status of site manager will have some system-specific experience.