Clerical Medical Investment Group Ltd v Crest Nicholson (South West) Ltd & Ors

A new headquarters building for the Claimant, Clerical Medical Insurance Group (CMIG), is under construction at Harbourside in Bristol. The building, known as "Building 12", will provide about 170,000 square feet of air-conditioned office space and will provide accommodation for about 2000 people.

Construction commenced in June 2004 and the project was due to be completed in late April 2006, but is not yet complete. Disputes have arisen in relation to the heating and cooling systems in the new building, and CMIG has commenced proceedings in which it seeks declarations against a number of parties:

The declarations sought are set out in the Appendix to this judgment and concern two distinct items. First, there is an issue which relates to the performance of the chilled beams ("the chilled beams issue"). This concerns a question of whether the chilled beams should be designed to achieve a temperature of 22°C (plus or minus 2°C) in winter. The second issue concerns the extent to which the cooling system should be designed to take account of the use of manual blinds at the external windows ("the blinds issue").

Initially it appeared that some parties might object to the jurisdiction of this court to make declarations in this case. However, all parties now accept that I have jurisdiction, though reservations are still expressed, particularly in relation to the blinds issue, as to whether it is appropriate for me, in my discretion, to make any declaration.

Proceedings were commenced on 19th May 2006. Pleadings, witness statements and experts' reports were exchanged, and the hearing took place on 4th, 5th and 7th September 2006.

I heard factual evidence from three witnesses. First, CMIG called Mr Ian Wilson, a consultant with RW Gregory LLP, consulting building services engineers, who were instructed in December 2002 by CMIG's parent company, Halifax & Bank of Scotland Group PLC ("HBOS"), to act as a member of the employer's agents' team for Building 12.

Secondly, Kier called Mr Jolyon Martin, a managing estimator, who had been involved in the project on behalf of Kier since late July/early August 2003.

Thirdly, HLP called Mr Saul Tyler, who had been employed since 2001 as an executive mechanical engineer and is an associate in that firm.

As I shall indicate below, this is not a case where factual evidence is of critical importance. Rather, the factual evidence described the involvement of the relevant people in the process which led up to the preparation of certain documents which I have to construe in this matter. It also related to what happened subsequently. I accept that in their evidence the witnesses gave their honest recollection of the facts of their involvement.

Expert evidence was of more, but still limited, relevance to the issues. There were four expert witnesses. CMIG called Dr David Arnold, a partner in Troup, Bywaters & Anders. Three experts were called by the Defendants but, sensibly, following the pre-trial review, the Defendants chose one expert to be the lead expert, with the other experts giving evidence in support. The lead expert was Mr Barry Gore, Chairman of Waterman Building Services Limited, who was called on behalf of HLP. In addition, Mr David Rollason, a Regional Director of White, Young & Green, was called on behalf of Kier and Mr Terry Dix, a director of Arup, was called on behalf of Crest.

The experts very helpfully prepared a note of agreements between experts dated 27th July 2006, which indicated the scope of agreements and differences between them.

Whilst the matters of construction of the agreements are questions for me to decide, I have been assisted by expert evidence on three particular aspects:

I found that all the experts provided cogent evidence on these issues, based on their long experience of building services design. However, to the extent to which the experts, in particular Dr Arnold, gave evidence of how they would construe the contract, such evidence amounted in effect to matters of legal submission. Whilst I understand the wish for a party to know how an expert would construe or interpret a contract, I do not consider that that assists me or is a valid area for expert evidence. Rather, I need to apply the legal principles with the background knowledge helpfully provided by those experts.

I now turn to consider the contractual position. There are two central agreements: the AFL and the Building Contract.

The AFL was executed on 17th March 2004 and was subject to supplemental deeds on 14th April 2004, 25th June 2004 and 17th January 2005. Under the AFL CMIG agreed with Crest to take a 25-year lease of Building 12 once it was completed.

The specification for Building 12 under the AFL is divided into two parts: the Category A work specification and the Category B work specification. The Category A work specification comprises the specification for the structure and envelope of Building 12, together with the fitting-out of such matters as M&E services, raised floors and ceilings, which were to be done by Crest. The Category B work specification contains CMIG's individual requirements for Building 12, as tenant, in relation to features such as meeting rooms, restaurants, computer rooms and cellular offices. Under clauses 6.1 and 33 of the AFL Crest were to carry out these Category B works only if instructed by CMIG to do so. It appears to be common ground that they were so instructed.

The Building Contract was a design and build contract between Crest, as the employer, and Kier, as the contractor, on an amended 1998 JCT Standard Form, incorporating the employer's requirements and the contractor's proposals, which together defined the works.

In addition, there were the following other agreements:

The air-conditioning which forms the relevant part of the service installation for the purpose of these issues consists of a system which provides a temperature-controlled environment using chilled beams to provide cooling throughout the offices and trench heaters around the perimeter of the building beneath windows to provide heating in winter. The chilled beams are cooling units that are concealed above a ceiling. They operate on the principle of natural convection. Chilled water is circulated through a serpentine pipe coil, which has fins on the outside. Air around the coil is cooled, and the cool air descends by convection into the office space through the ceiling. The rate of cooling that a chilled beam can provide depends essentially on the temperature difference between the temperature of chilled water circulated through the pipe coil and the temperature in the building. As the temperature in the building increases, the rate of cooling from the chilled beam increases and, as the temperature falls, the rate of cooling decreases.

The system in Building 12 uses adjacent harbour water during the colder periods and this reduces energy usage, in keeping with CMIG's desire for the building to have at least a “very good” BREEAM (that is Building Research Establishment Environmental Assessment Method) rating. A BREEAM rating assesses the building's overall environmental impact, taking into account such matters as energy use, the inclusion of sustainable source materials and measures adopted by building users.

As I have said, both heating and cooling systems are present in the perimeter zone of the office spaces within Building 12. However, the deep plan internal areas, which occupy approximately two-thirds of the office space, require cooling all year round and there is no heating system within these areas. This is a consequence of the amount of heat generated by office equipment, lighting and occupants and the relatively high standards of thermal insulation in a sealed building with no opening windows.

Essentially there are two sets of obligations, one set which is derived from the AFL and one set which is derived from the Building Contract. No party contends that different obligations are imposed under the two agreements, and CMIG contends that all parties are in any event bound to comply with each of the documents in both the AFL and the Building Contract.

I therefore approach the questions of construction which arise under the two issues on the basis that, whilst there are two separate sets of obligations, there are no relevant differences in the scope of the obligations, and, in fact, this is confirmed by my analysis.

The rules for construction of contracts are now tolerably clear, and the parties have referred me to Lewison on The Interpretation of Contracts, (3rd Edition), and relevant authorities, which establish certain principles. Those principles are:

In this case those principles raise two particular issues. First, I have to consider the meaning of a mechanical services specification. That is a matter of ascertaining the meaning to a reasonable person who has the necessary background knowledge in mechanical services. In this case all parties would have had or did have available to them such background knowledge at the time when they contracted.

Secondly, in terms of matrix, there is very little relied on which could be of assistance. The one contested issue is whether the "greenness" of the project is a matter which should be taken into account, given that this project was described as "Project Green". The question is whether this is a relevant factor in deciding on the meaning of the contractual obligations.

At paragraph 18 of their closing submissions Mr Darling QC and Ms Lemon for CMIG summarised the evidence and submitted that there is insufficient evidence to tip the scales one way or the other. Mr Cross, who appears for HLP, and whose submissions were in general terms adopted by Mr Streatfeild-James QC and Ms Slow, who appeared on behalf of Kier, and by Mr Taverner QC, who appeared on behalf of Crest, referred me to the BREEAM documentation.

I have come to the conclusion that there is strength in the submission that the common intention was that a high BREEAM rating should be obtained for the building and that, for instance, through the use of cooling water from the harbour and solar collectors on the roof there was an intention to have a building which was sustainable and had low energy usage. Indeed, this intention appears to be accepted at paragraph 16 of CMIG's closing submissions.

However, I accept that, as Mr Darling submits, it is only likely to be in cases where two meanings are finely balanced that the intention to have a sustainable and low energy usage building is of any relevance, and that in achieving a Category A building there will be cases where that intention cannot be achieved.

Mr Cross referred me to a good deal of post-contractual material, but I have come to the conclusion that this does not assist in the questions of construction with which I am to deal. It is the intention of the parties at the time of the agreements which is of relevance.

There are certain documents which are referred to within the contractual documentation and which provide general guidance on the aspects with which I am concerned. They are, therefore, relevant not as imposing obligations but as an aid to interpretation. In this case they consist of three documents: The CIBSE Guide A, 6th edition, 1999; the BCO Guide 2000 and British Standard 7730, 1995.

With all those various matters in mind, I now turn to consider the issues and the relevant documents.

The chilled beam issue concerns the internal design temperature which should be complied with by the cooling system in winter. CMIG contends that it should be 22°C dry resultant temperature (DRT) and the Defendants say it should be 24°C DRT.

In the Category A specification, section 4 deals with mechanical engineering services. Clause 4.1 provides for the scope of mechanical design work. It states:

Clause 4.2 then deals with design criteria. It first sets out external design conditions in these terms:

It then states that the following external design conditions will be adopted:

Clause 4.2 then continues and specifies internal design conditions and states:

The relevant reference for the purpose of the issues in this case is to the general office areas, where winter design temperature in degrees Centigrade is defined to be “22 ± 2” and summer design temperature in degrees Centigrade is defined to be “24 ± 2”.

The provision then continues:

Clause 4.6 of the Category A specification contains a description of the central low temperature hot water (LTHW) heating system. The opening words are as follows:

It then describes the boiler plant, primary LTHW heating distribution circuit, pumps, constant temperature LTHW heating circuits, perimeter trench heating, radiators and pipework. In other words, it covers all aspects of the system.

Clause 4.8 of the Category A specification then deals with the central refrigeration and chilled water (CHW) cooling system. It states in introduction:

Like the central LTHW system, it describes the chillers, pumps, pressurisation, chemical dosing, de-aerator and filtration units, headers, pumps and secondary distribution circuits. Of relevance it also states that cooling to the office areas will be via static cooling devices, a combination, at that stage, of chilled ceilings with perimeter chilled beams.

Clause 4.9 of the Category A Specification then provides further definition of the chilled beams.

The Category B specification at section 6.2 and in the room data sheets contains a reference to design criteria for the open office space and states that the temperature in degrees Centigrade in summer is “24 ± 2°C” and in winter is “22 ± 2°C”. This is consistent with the reference in clause 4.2 of the Category A Specification, and I do not consider that it adds any new or further obligation to those in that Category A specification.

The central issue is, therefore, a matter of construction of section 4 of the Category A specification. As clause 4.1 says, the provisions of that clause detail the mechanical engineering systems to be designed within the building. The reference to design criteria in clause 4.2 is, I consider, just that. It sets out criteria which have to be applied to the design of the mechanical engineering systems which are described in the following sections. These criteria therefore have to be read in the context of those sections.

In my judgment, clause 4.6 makes it clear that the central LTHW heating system will be provided "... in order to maintain the internal winter design conditions detailed in the design criteria of this report". I consider that this states, in clear terms, that the heating system has to be designed to 22°C (± 2°C) for the general office areas.

Clause 4.6 contains a reference to perimeter trench heating, which forms part of the central LTHW system and has to be designed to 22°C ( ± 2°C).

Similarly clause 4.7 makes it clear that the central refrigeration and chilled water cooling system will be provided "... to maintain the internal summer design conditions, that is 24°C ( ± 2°C)."

That clause also contains a reference to cooling being by a combination of chilled ceilings (subsequently changed to chilled beams) with perimeter chilled beams. As part of the cooling system the chilled beams have, in my judgment, to be provided to maintain those temperatures of 24°C ( ± 2°C), just as all the other components have.

Dr Arnold, with some support from Mr Gore, indicated that he read clause 4.7 and other parts of the specification as only applying to central plant and the pipework distribution system. In the light of the express reference to chilled beams in clause 4.7 I do not consider that there are any grounds for excluding chilled beams from the obligation in the opening paragraph of clause 4. In the absence of a statement elsewhere that chilled beams are to be designed in a different way, there would be no provision which related to the design of chilled beams.

I do not consider that clause 4.2 contains a freestanding obligation to design everything, including the chilled beams, so that the winter design temperature is met. This would cause difficulties in knowing when the chilled beams would have to meet the winter and when they would have to meet the summer design temperatures.

The reliance by CMIG on clause 4.10 of the Category A Specification as providing a definition of when the building should be meeting winter or summer design temperatures is, I consider, misplaced and attempts to give that provision a role which it cannot have been intended to meet. That clause provides for the office ventilation system. It again commences with an introduction which refers to the design criteria which the system has to meet. It states:

As part of the description of the office ventilation systems it states:

I find no logic in attributing an intention to clause 4.10 of defining winter for the purpose of requiring the chilled beams to be designed to meet the internal winter design conditions during that period. I consider that the provision in clause 4.10 merely states that warmer supply air will be provided during cold periods in winter months.

The definition of a winter and summer design temperature was, as Dr Arnold accepts, originally applied in mechanical services design so that heating achieved the winter design temperature and cooling achieved the summer design temperature. This can be seen also in BS 7730, 1995, where at page 23 it states under paragraph D.1.1:

Paragraph D.1.2 similarly states in relation to summer:

I am conscious of the valuable point made by Dr Arnold that buildings have changed so that whilst before cooling was required only in summer and heating in winter, cooling in winter is now frequently required. That change in practice, in my view, underlines the need for clarity if cooling is to be set to achieve a lower winter temperature.

The experts are agreed on a winter/summer definition in their expert agreement in the following terms:

The CIBSE Guide and the BCO Guide, which are referred to in the specification, both refer to design criteria. In the CIBSE Guide A clause 1.3 states:

The CIBSE Guide then refers to various orders which prohibit the use of fuels or electricity to heat premises above 19°C. It continues:

Over the page then at Table 1.1 it sets out recommended comfort criteria for specific applications. In respect of offices under "Winter dry resultant temperature range for stated activity and clothing levels" a temperature is given of 21 to 23°C. For "Summer dry resultant temperature range for stated activity and clothing levels" a temperature is given of 22 to 24°C.

In the BCO Guide 2000, Best Practice in the Specification for Offices, the following is stated at clause 4.4.2:

I do not consider that, as Dr Arnold suggests, these figures point to the fact that a cooling system which only achieves 24°C in winter will mean that it is inconsistent with the CIBSE Guide and the BCO Guide. It is evident that the guides are just that. They allow for a designer to take into account such factors as predicted mean vote and percentage of people dissatisfied in assessing the actual design criteria for a particular project. Rather, I find that the approach of the specification in this case is consistent with the approaches in those guides, which are aids for the designer, not statutory requirements.

In addition, to the extent that the "greenness" of the project was relevant, I consider that there is force in Mr Cross' submission that it would be contrary to that intention, in the absence of a clear statement to the contrary, for the chilled beams to be sized to cool to a lower temperature in winter weather than in hotter summer weather. I, therefore, am supported in my conclusion by both the guides and the general intention, to the extent that I would otherwise need such support.

An issue is also raised as to the effect of the reference in the design temperature in clause 4.2 of the Category A Specification to a temperature of “± 2°C”. The experts are agreed that a design temperature is a dry resultant temperature and has to be distinguished from a control temperature, which is an air temperature. I note from the CIBSE Guide at section 5.1, to which I was referred, that it stated:

This indicates that, although the various temperatures have distinct meanings, they are sometimes combined. That, in my judgment, explains why clause 4.2, while referring to design temperature, also refers to a figure of “± 2°C”.

The experts agree in their joint statement that in clause 4.2 of the Category A Specification the fluctuation band/tolerance of ± 2°C accounts for variations in local air temperatures from the setpoint for control, for variations in temperature with height, distribution of sources of heat gains and loss in the space and response of controls.

I do not consider that the reference to ± 2°C under the design temperature can be taken to mean that the design temperature could be chosen at a level of 2°C above or below the DRT figure given. I consider that the reference is to the fluctuation band for air temperature in relation to control, as explained in the reference within clause 4.2.

I now turn to consider the provisions of the Building Contract as contained in the Contractor's Proposal. In particular in relation to M&E work it refers to the following:

Included within the first item are two specifications which are particularly relevant: T20 for primary/secondary heat distribution and T61 for primary/secondary cooling distribution.

Specification T20 sets out performance objectives at Clause 1000 in the following terms:

In Clause 2000 it then defines those internal design temperatures (dry resultant), which are as follows:

The system description at Clause 3000 again refers to perimeter heating by trench heating.

Specification T61 similarly sets out performance objectives at Clause 1000:

At Clause 2000 it then says:

The system description at Clause 3000 includes reference to chilled beams. I consider that, like the Category A Specification, the provisions of specifications T20 and T61 are clear in their intention that the primary/secondary heat distribution system was required to maintain the space temperatures of 22°C (±2°C), and the primary/secondary cooling distribution was required to maintain the space temperatures schedule of 24°C (±2°C), which are expressly referred to as summer internal design temperatures.

I can see no obligation to provide space cooling requirements to maintain the space temperatures of 22°C. Again the reference to "± 2°C " is, in my judgment, a reference to control temperature. Equally, I do not consider that the provisions of these specifications somehow exclude the terminal points, that is the trench heaters or the chilled beams, from the obligations to design to the stated temperatures. Nor do I think that, instead, they impose a general obligation, which is freestanding, for all of the terminal points to achieve both the summer and winter conditions.

The second item of the Contractor's Proposals is the revision changes schedule for Stage E design, which contains three items to which I have been referred as being relevant: Items 37, 53 and 146. These items relate to comments raised and answered relating to the specifications.

This arises from specification T61. It comments: "See RDS [room data sheets] for design temperatures and loadings." The response is: "Noted." Those room data sheets, as I have said, state typically under "Room temperature control": "Winter: 22°C ± 2°C; Summer: 24°C ± 2°C."

T61 refers to summer internal design temperatures, and I consider that the comment in item 37 was made to ensure that the summer design temperatures in T61 were consistent with the summer temperatures set out in the RDS. It did not, in my judgment, intend to amend T61 by requiring the colloling system to comply with winter internal design temperatures, which would, I consider, have imposed a new and fundamentally different requirement.

This arises from drawings showing high level mechanical services, levels 1 to 3: drawings M330P1 to 332. Drawing M330P1 showed the high level layout of the chilled beams and included a diagram of "Chilled beam/trench heater local temperature control principle for given zone". It shows the chilled beam "on" if "T > 24°C" and the trench heater "on" if "T < 20°C". The comment at item 53 is: "The chilled beam heating control set-up will not meet the AFL." The response was: "Agreed: Chilled beam on temperature amended to 22°C."

CMIG says that this indicates that the intention was to have the cooling system operating at 22°C, which is consistent with the application of the winter temperature of 22°C to the design of the cooling system. I do not accept that. I do not consider that this provision, which relates to control, can impose an obligation to design the system to a design condition which is not specified for that system. It seems to me that the various statements within the contract as to control are neither consistent as between themselves nor provide support for the case of either party.

I accept that a control set-up which is set to come "on" at a temperature greater than 22°C would be expected to achieve 22°C, but equally a control set-up for the heating to come "on" at a temperature less than 20°C would be likely to achieve 20°C.

I consider that it is likely that an assumption was made that to achieve a temperature of 24°C a setpoint of 22°C would be required and that to achieve a temperature of 22°C a setpoint of 20°C was necessary. Whether this was on the basis of heat coming on before the temperature was reached or cooling coming on at a lower temperature to achieve a higher temperature is not clear.

However, if CMIG were correct, then the drawing would require two conditions, one which required the cooling to come on at a particular temperature if the summer requirement applied and another if the winter requirement applied. Whatever else it meant, it did not mean to impose such a requirement.

This arises from the automatic control specification, W62. It comments:

Specification W62 includes the following provision at Clause 5570:

This is another provision which is dealing with control temperatures. The comment criticises the use of a temperature of 23.5°C for heat to go off and a temperature of 24.5°C for cooling to come on. This is inconsistent with the diagram which is the subject of item 53. However, it appears to confirm that 24°C is the relevant temperature.

CMIG also refers to two other provisions of specification W62, which it says relate to a temperature of 22°C:

Again these are consistent with a control philosophy which requires action in relation to cooling when a temperature of 22°C or 23°C is reached. Whatever the control method being used, I do not consider that provisions in specification W62 relating to automatic control can affect design temperature or impose an obligation to design the system in a manner inconsistent with specification T20 or T61. They are concerned with a control philosophy which, at the very least, appears to be unclear.

Two further documents have been referred to. First, schedule M14, which deals with fan coil units. This has been referred to by CMIG. It shows winter and summer room temperatures of 22°C and 24°C. Some of the fan coil units have cooling and heating. Some have only cooling. Whilst that schedule sets out the temperatures, it does not state that the cooling has to achieve the winter temperatures. I do not consider it assists in the interpretation of the design obligation.

The second document was schedule M20, which schedules chilled beams and refers to a space temperature of "24°C ± 2°C ". I consider that such schedules have to be read in conjunction with the underlying design obligation and I do not gain assistance from the schedules. I do not consider that they change the underlying obligations as I found them to be.

In summary, therefore, I consider that the provisions of section 4 of the Category A specification are consistent with specification T61 in imposing an obligation to design the cooling system only to achieve the summer design temperature of 24°C. I do not consider that these provisions or any of the other documents referred to impose an obligation to design the cooling system to achieve the winter design temperature.

This issue raises questions which are said to arise as a matter of construction of the agreement and as a matter of standard practice. The first issue raises a point of construction on whether under the Category A and B specifications the blinds are only to be used for manually-operated solar glare control and not to be taken into consideration when sizing the chilled beams in the office areas.

It is common ground that the specification is silent as to any requirement on the use of the blinds. CMIG submits that the absence of any requirement on the use of the blinds means that there is no specified requirement for CMIG to use blinds and, therefore, no limitation on the use by CMIG of the building. CMIG also points to the fact that there are requirements in the specification which show that solar gain was to be dealt with by the brise-soleil and submits that the fact that such a positive statement is made is to be contrasted with the fact that there is no such positive requirement in relation to blinds.

CMIG also relies on the references in the specification to the blinds being for the control of solar glare, which is to be distinguished from solar radiation control.

The blinds were part of the Category B Specification and CMIG points out that these were its own fit-out works and that it could have omitted the blinds if it had wished to do so. The Defendants, on the other hand, rely on the fact that the AFL requires the installation of blinds and there is nothing in the Category A or Category B specifications which limits the ability to take the blinds into account when sizing the chilled beams.

The Category A Specification at section 7.02 of the architectural specification includes the following provision for glass:

It also includes a provision for solar shading to the southern elevation between 1st and 3rd floors in the form of vertical stack brise-soleil.

At section 3.0 of the mechanical and electrical specification dealing with the building envelope it is stated at clause 3.3:

In section 5 of the mechanical and electrical specification dealing with electrical engineering systems it is stated at clause 5.3.6:

The Category B Specification included a requirement for blinds. At clause 3.2.12 it required: "Blinds to all external windows for localised glare control." At clause 4.2 it stated that:

At clause 4.4.1, describing the open plan office, typical floors, first and third floors, it stated:

The room data sheets provided typically under "Blinds" that they were manual with a specification as follows:

From these provisions it is apparent that the Category A Specification did not contemplate the use of blinds as a requirement, because this was a matter for the tenant. The tenant, however, did include a provision for blinds in the Category B Specification. Once included in the Category B Specification,which became part of the work, then the provision of blinds would become part of the works to be carried out, and there would have to be a change process for the blinds to be omitted from the work. I do not accept that the fact that blinds are in Category B Specification alters any obligations with which I am concerned. Whilst the tenant included the blinds for the purpose of glare control, the particular blinds to be used are also specified and refer to solar control fabric.

A specification in a design and build contract contains a mixture of provisions. It includes, as in this case, specific requirements which have to be provided, such as the blinds. It also sets out requirements which have to be taken into account generally in carrying out the design of the works. For instance, the fixing for the blind must be able to withstand the weight of the blind and an allowance for the force exerted in operating the blind. In addition, the specification contains a number of specific items which have to be taken into account in carrying out the design.

In designing the works, the party responsible for the design must, therefore, take into account the provisions of the specifications in a number of ways. There will be express requirements and express prohibitions. However, within what might be described as the "design envelope" defined by the specification there will be a number of assumptions which a designer has to make, which will be derived from the specification. In this case, as developed in argument, the specification appears to have defined a number of these assumptions and, therefore, has limited the envelope within which the designer can make assumptions.

In the case of blinds there is no such limit. As phrased in the declaration, the issue is whether the specification limits the extent to which the blinds can be taken into account. The fact that a tenant wants a blind for solar glare control does not, in my judgment, provide a limit on the designer's ability to take into account the particular properties of the type of blind which is being specified, including control of solar gain. The purpose within the specification of the reference to glare control is as a preamble to the obligation in this case to supply a particular type of blind.

I do not consider, therefore, that the terms of the specification limit the extent to which the designer can take account of the properties of the blind. Indeed, I consider the designer is under an obligation to take into account all relevant properties of all relevant items of the specification when he is carrying out the design. I see no reason why, in principle, a designer cannot take into account the properties of the blind when he is carrying out his design of the cooling loads for the purpose of sizing the chilled beam units.

The declarations, though, also raise a different issue, that of the extent to which a designer can properly take into account the use of blinds.

In the context of whether a court should grant this type of declaration I have been referred to the words of Lord Diplock in Gourlet v The Union of Post Office Workers [1978] AC, 345 at 501, where he said this:

Secondly, I have been referred to the decision of the Court of Appeal in North West Thames Regional Health Authority v Sheppard Robson [1995] 50 Con LR 79 in support of the proposition that the courts do not generally make declarations of future rights which are no more than hypothetical or which are merely a prelude to further proceedings where issues of negligence may be raised.

In particular, in this case, I am concerned whether the issue of standard practice can properly form of the basis of a declaration. First, standard practice is a difficult concept and may vary widely, depending on the particular factual circumstances. Secondly, it is a question of fact, not a question of legal right. Thirdly, the issue is evidently a prelude to a claim based on the specification.

At this stage and in the context of the type of declaration being sought it is not possible to assess what will be said to be the future legal consequences of a standard practice. For instance, is compliance with standard practice a defence to a claim for a breach of the terms of the specification or does it give rise to implied obligations or have some other legal consequences?

Having heard the expert evidence in this case, it seems to be common ground that in carrying out a design of a cooling system consideration would be given to and assumptions made on the use of blinds. In any given circumstances the assumptions to be made will depend on a complex interaction of the legal rights and liabilities and the particular facts.

As the case based on legal obligations develops, there may, for instance, be an issue whether a particular party is limited in the assumptions it makes as to the use of the blinds by, for example, the use which a reasonable user would make of the blinds or the use which a user might reasonably be required to make of the blinds, or the use which a party might be entitled to specify in a document such as a building user's guide. In relation to the latter, I was referred to the BREEAM document at reference MAN 1-5, which deals with the contents of the user guide in these terms:

Whilst in this case I quite understand the importance for the parties to know what assumptions might properly be made, I do not consider that the court should make binding declarations which are not firmly grounded upon particular legal obligations. To do so is likely to have unfortunate consequences in any future proceedings, not least because the impact of that declaration on any particular future contentions would be uncertain.

In certain circumstances, through such methods as early neutral evaluation, the TCC may be able to deal with such issues, but the route of making binding declarations is not, in my judgment, available.

In conclusion, as I indicated during argument, I propose that the parties should seek to agree the form of the declarations that arise from this judgment. Subject to that, I consider that: