The function of a controls specification is to pass on the client ‘s demands and supply a complete and unambiguous definition of the edifice control system ( 1 ) . In other words it describes the characteristics and public presentation demands that the client has requested within the client brief. Further to this it besides contains information on the criterions that need to be attained ; the testing and commissioning that is to be carried out to guarantee the system is working right, and preparation of the terminal user to guarantee that they will run the system expeditiously and to accomplish the coveted comfort conditions. It besides plays a portion in specifying duties at different phases of the control system installing and the procurance procedure.
The specification needs to be clear, precise and direct so that it provides all of the necessary information but without being excessively complex.
There are 2 general types of control specification, either public presentation or functional. In pattern most controls specifications are intercrossed specifications of the above containing elements of both.
By and large talking a public presentation specification is used to depict what tasks the controls system should be able to transport out and besides what equipment each system is to command.
A functional specification contains more elaborate information on how the system should work including monitoring and control of information for specific points of equipment ( e.g. boilers ) and descriptions of parts of the controls system such as the detectors, outposts & A ; actuators.
By and large a public presentation specification is a looser specification than a functional specification, this means that there is more range for mistake ; nevertheless a public presentation specification is acceptable if the needed system is reasonably simple or there is an component of trust between the controls contractor and the writer of the controls specification. The large disadvantage of a functional specification is that the writer requires elaborate cognition of controls engineering which many M & A ; E advisers may non hold, besides as with IT in general the field of controls is developing really fast and as such information becomes excess rapidly.
Some of the issues that may necessitate to be considered when fixing a specification are as described below:
The controls specification would usually include information on the needed internal comfort conditions, and environmental tolerances ( what discrepancy from the specified set point is acceptable ) . These are the most of import facet of the controls system and demand to be taken into history within the specification. Specific comfort standards can be taken from CIBSE Guide Angstrom: Environmental Design.
Some countries of a edifice may necessitate to be controlled independently to the remainder of the edifice due to assorted grounds, including ; different hours of tenancy, different usage of the edifice, such as computing machine suites, and besides different demands of the residents.
It is of import to guarantee that these standards are realistic and accomplishable since if they are non than hapless system public presentation and reduced works public presentation may ensue which in bend can take to increased energy use and running costs.
The controls system needs to be flexible in footings of being able to suit the hereafter plans for the edifice. Over the life-time of a edifice it can be altered significantly. The layouts of the edifices can alter, the usage of the edifice can alter and besides the system demands can alter hence this needs to be clearly identified within the specification as future proofing the controls system at the clip of installing can salvage a batch of clip and money subsequently on.
The specification would besides incorporate information on dismay end product standards such as dismay set points, actions, texts, and managing. These are used to describe works mistake conditions or out of set tolerance warnings, how end products are presented to the user ( on screen, printouts etc ) , and what should be done to rectify the dismay.
The specification should besides cover integrating of the controls systems for assorted edifice services systems such as the warming, chilling and airing works with other systems such as fire, security, entree control and lighting.
Without a good quality specification a batch of possible issues can happen such as, hapless environmental comfort due to inadequate control systems being in topographic point, inordinate energy use and hence unneeded costs and besides occupant dissatisfaction due to uncomfortable on the job conditions. Any alterations to the control system during the building procedure may significantly increase the cost of a control system.
3. Undertaking B
Describe the criterions to be met, including testing, commissioning and preparation to be carried out and the warrants to be given:
The controls specification will include inside informations of criterions to be met by the controls system, these can include relevant British Standards ( such as EN 13646:1999 – Building Control Systems and EN ISO 16484-2 – Building Control Systems Part 2 ) current Building Regulations ( such as Part L ) , local by-laws, CIBSE Guides ( such as usher A and H ) , and BSRIA publications. ( 2 ) Refer to bibliography for list of farther relevant British Standards.
Commission is the procedure of puting up the controls system to guarantee that it works as it is required to by both the client brief and the controls specification. It is a 2 phase procedure consisting Pre-Commissioning and Commissioning.
Pre-Commissioning is the procedure of look intoing that all the constituents of a control system work right by bench proving and site testing. Bench testing is done pre installing and is done to guarantee that equipment such as detectors and valves function as they are supposed to and are non defective ( maker mistakes ) , site testing is chiefly to guarantee that the constituents have been installed right ( e.g. look into a detector is wired up decently, no installing mistakes ) .
Commissioning involves puting up the control system as a whole to guarantee that all the constituents work together, including the BMS supervisor ( the computing machine that acts as the encephalons of the BMS ) and the head terminal ( the input/output device for the BMS such as a GUI – Graphical User Interface ) . The operational control parametric quantities for assorted pieces of equipment must besides be set ( such as temperature set points ) to guarantee all the constituents of the system work together as they are supposed to. As a note all works equipment must hold been commissioned before the control system can be commissioned, besides it is of import at this phase to input the right operational parametric quantities as really frequently the scenes are non altered by the user after commissioning.
Once a system is commissioned to the satisfaction of the installer, witness testing is carried out. Witness proving can be overseen by the undertaking supervisor or his nominative representative and is to turn out to the satisfaction of the nominative representative that the system is runing right. This can include guaranting works and equipment is installed as per the controls specification and proving operator / user controls and interfaces. By and large the nominative representative should witness test the control of all major works points and depending on the size of the control system they should besides witness trial a per centum of other control points. They should besides witness a per centum of system end products such as works dismaies and safety dismay responses ( works shutdown ) .
A BMS system will merely execute right and be cost effectual if its operator knows how to command it. For this ground operator preparation is required. The client must make up one’s mind if they wish to straight use the operator or if they want to use a contracted direction company. The cost of preparation to be provided will straight associate to the required accomplishment and cognition of the operator.
The control system should be provided with a warrant by the system installer which is to guarantee that the system will execute as detailed in the controls specification. The warrant will besides cover control equipment maker guarantees.
Once all the above has been done so constructing handover can be completed and a practical completion certification issued.
4. Task C
Describe its function as a portion of the procurance contract between the buyer and the provider / installer:
There are 4 chief types of procurance procedure within the edifice industry:
Design & A ; Build
Design & A ; Manage
The traditional and Design & A ; Build type procurance contracts the most common within the UK.
With design and physique, the client places a contract with a individual contractor who has duty for both design and building. The client may name an advisor to move as employer ‘s agent, to rede on the readying of the client ‘s brief, rating of stamps and to supply independent advice throughout the undertaking. Design and physique has advantages:
The client has individual point duty from one administration
As the contractor has duty for both design and building, economic systems should be possible
A well-written client ‘s brief is indispensable to the accomplishment of a satisfactory controls solution in the concluding edifice ; an inadequately elaborate initial brief may take to the contractor supplying an absolute minimal specification. A fluctuation is known as develop and concept, where the client uses a design adviser to bring forth a range design, before obtaining stamps from contractors who develop and complete the design and so build the edifice.
The traditional procurance method separates design from building. The client appoints design advisers who prepare a elaborate design of the edifice. The design is put out to tender, following which a chief contractor, responsible to the client, is appointed. The chief contractor may name subcontractors. During building, the design advisers exercise a supervisory function. This method is good understood in the UK and has the advantages of:
Supplying clear contractual duty for each facet of the work
A well-understood process
From the controls point of position, it has disadvantages:
There is no engagement of a specializer subcontractor at the design phase
Alterations to the design during building are expensive
The controls specification forms the footing of a contractual understanding between the client and the contractor which forms portion of the procurance contract. This function does non change between different types of procurance contracts, what does alter is the design duty. So if utilizing the traditional contract so the duty is with the clients design adviser within the design squad. If a D & A ; B contract is used the duty is with the contractor.
Responsibility diagram for the traditional procurance method. ( 3 )
Responsibility diagram for the design & A ; build procurement method. ( 4 )