This topic follows on from the recent general advice on things to budget for when planning a house build. The amount set aside in a contract or tender for a specific product is called a Prime Cost Sum, or p.c. sum. Contractually this means that it is a sum put in the contract to be expended at the discretion of the client for a specific purpose. If you do not spend the full amount, the difference is taken off or added to the final account. Your quantity surveyor will also provide a line in the Bill, sometimes called profit and attendances, that is an amount the main contractor puts in, related to your p.c. sum, to cover organising and installing that item.

When I am preparing a client budget for a project or tendering a project later on in the process, I always include specific amount for bespoke lighting, over an above the general allowance for electrical works. This is so that there is a ring-fenced amount in the client’s mind for architect-designed feature lighting.

Feature lighting is extremely important in architecture, because if done right, it adds a disproportionate feeling of quality to the whole works, over and above the relatively small investment, compared to other architectural gestures such as finishes, spatial drama, quality fittings etc. If you spend money or design budget on the above, and do not light them effectively, they can fade into the background. The space may have no ‘punch’.

It is important that the budget has this as a separate element at the earliest stage, separate to the general electrical sum, because during the development of a design and its budget, cost savings are usually introduced. The electrical budget will no doubt come under pressure, and if it is, when it comes to doing a detail design for lighting design, the budget will have been exhausted before it comes to designing these features, and often good lighting will not happen. The result is that even interesting architectural features can come across as pedestrian, as the lighting does not do it justice.


Bespoke lighting can perform a number of similar functions, and in every project I try to identify what might be most effective or appropriate event to integrate special lighting in an unexpected way.


The first image above shows a suspended timber skeleton holding a l.e.d. strip. The light is at the inverted apex of the two sloping ceilings either side, which has been truncated by the horizontal ceiling section around the light. The whole light installation makes for a ‘ghost’ completion of the angles. This is purely a piece of architectural theatre.


The detail below is a l.e.d. strip in a handrail recess. The ambulant stairway to a first floor apartment is required by regulation to have handrails both sides, and achieve a certain clear-width. The solution here was to recess one handrail. Rather than do this in a dark shadow filled void, the application of the light highlights the void and turns it into a very cool feature light which at night draws you from the front door up to the accommodation level.


This third example is a steel beam which supports the whole house above and the cantilevered extension. The l.e.d. lighting strip on the lower flange of the steel illuminates the web of the beam and upper flange, so that the beam itself becomes the luminaire, and throws light horizontally across the ceiling.

This lightens the structure and declares it as an element integral to the space.


I would love to hear your comments on lighting design and project budgeting and if you have any questions post them in the comments below and I will get back to you. Thank you for reading my blog on this issue and do share it using the buttons opposite!

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