LETTERS
The need for a lighting review

Dear Sir,
We need to change the way that we assess project costs.

The old cost comparison model is based on the ‘blanket design’ approach. We light an entire room to a particular illuminance for a particular period of time – usually the wholeworking day. That only requires a simple bit of mathematics to translate the physical situation into a projected kilowatt-hour cost.

Payback periods for better (moreexpensive) technology could be worked against that model, but now we’re contemplating a high energy-cost future in a low-carbon environment that model no longerserves.

We need to squeeze the last drop out of the ‘lamp + control gear + luminaire’ hardware, and that means we must ensure that we’re using the best that product design has to offer, and there’s a cost associated with that. But we also want to reduce the length of time that we use the hardware, and even have the facility to reduce the luminaire’s output when required.

That means we spend more money on our luminaire and our control arrangements and we only begin to see the savings thatwe’re making when a proper life cycle assessment is made of the installation.

Arguing the low-unit-cost against the ef cient high-tech model no longer works for us, and it’s going to be a bit of an adventure seeking out a new model that does work.
John Bullock
Dorchester
Dorset

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