station within a building. It is not unusual in large buildings in London for example, to have a centralised control station housing dozens of instruments together with flashing lights, klaxon alarms, etc. In the author's opinion a central station should include 'master' safety alarm devices and not all the multiplicity of individual alarms.
By adopting this arrangement, the number of instruments to be provided is reduced and in the event of an alarm signal being received it ensures the operator visits the plant to determine which particular alarm has caused the master alarms to actuate.
Fault analysing instruments and devices should be centralised for buildings such as hospitals, etc. for reasons previously mentioned, but for ordinary commercial buildings the decision to install the instruments must take into account capital cost against the essentiality of this provi- sion.
Unless the centralised station is to be a 'show-piece' (and some most certainly are) then there is very little case for providing 'fuel saving' in- struments at the station. On the con- trary the provision of these instru- ments at a centralised station, as op- posed to providing them locally to the plant concerned, not only costs more but enourages the plant operators to become 'chair-bound' which is highly undesirable from the point of view of inspecting and maintaining the various plants.
Other engineering services
Among the other services that could be encountered in a building would be such provisions as steam, compressed air, centralised vacuum, fire services, diesel generators for the production of electricity, chilled drinking water, etc.
In fact the engineering services that are provided in buildings would make a very extensive list and al-
AREA
GROUP
1. Safety
2.
Comfort and Wastage
3. Fuel Saving
4.
5.
Fault Analysing
Labour Saving
TABLE No. 3.
TYPICAL EXAMPLES
Safety valve, shut-down thermostats, fire alarm, lift alarm, C. O. indicators
Room thermostat and humidistat for air-conditioning control
Boiler gas Co2 and temperature recorder. Ammeters for motors
Pressure guages, thermometers
Remote instruments, i.e. thermometers, pressure guages, etc. with indicators at centralised station
though these have not been mention- ed in detail this should in no way detract from the importance of such services.
Cost of engineering services
The cost of engineering services for a building will depend on the type, scope and complexity of the systems to be installed and this in turn is de- pendent on the requirements of the building and also to some extent the building design.
The cost of engineering services is quite often expressed in terms of dollars per ton of air-conditioning or dollars per lighting fitting or power point, and on this basis the total cost of the service concerned is approxi- mated.
This practice is convenient for engineers and architects but can be extremely misleading to building owners, as quite often they will con- sider the proposals of the engineering work purely on this method of price cstimating.
The true cost of an engineering service must take into account all factors and these would include the following:-
(a) The type of system that is being considered. For exam-
TABLE No. 2.
Pressure to be achieved in
relation to
ambient
Approximate air changes per hour
Basis of Calculation
Kitchens
Negative
20
To remove kitchen fumes and steam, to limit temperature
Toilets
Negative
6
To ensure fresh atmosphere
Boiler
Positive
12
Rooms
Garages and
Negative
8
Connecting
Tunnels
Sufficient air for combustion
To limit to safety level of C. O.
ple, in the case of air-condi- tioning whether the proposals are for an 'all air system' or a chilled water fan-coil ar- arrangement.
(b) The standard of materials that are being used and the grade of workmanship that would be employed for the installa- tion of the work.
(c) The operating cost of the ser- vice, that is, the electrical consumption, repairs, main-
tenance, etc. (d) The space requirements of the service concerned and the re- lative value of such space compared to the varying de- signs and costs of the service. As an example, although high velocity air ductwork compar- ed to conventional ductwork is more expensive both in capital and operating costs, an overall saving may be made due to the reduced space re- quirements.
Although the practice is now rapidly dying out there are still a few unfortunate cases where the architect for a building treats the cost of the engineering services as a sort of con- tingency sum for the building.
The effect of this is that should the architect have a change of mind dur- ing the building design which neces- sitates an extra expenditure then an attempt to meet this is made by reducing the cost of the engineering works.
However, it can generally be said that with engineering services, 85% of the cost is in the basic necessities of the service, 10% is attributed to the standard of workmanship and materials and the remaining 5% is expended on the finishes and neatness of the installation.
A reduction in cost of the services not only means a lower standard of workmanship and materials but also a reduction in the services provided which can affect the functionability of the system which may well have to be paid at some later date by the building owner in terms of main- tenance and replacements.
Far East Architect & Builder October, 1965
75