Can Smart Lighting Become a Carbon-Management Tool for Net-Zero Buildings?

Hi,

If as you propose, lighting could be "optimised" (and I think you actually mean reduced) in response to high carbon generation then why shouldn't that optimisation persist continually, saving energy (and thus money and carbon) all the time?

I would suggest that the possibility that the lighting could be "optimised" whilst still meeting the design requirements suggests that the original designers failed to optimise it in the first place, or that the cost of optimising it was large compared to the energy (and hence carbon) savings which might be achieved.

Sorry this response isn't as positive as you might hope.

Thank you for the constructive feedback, I appreciate the challenge, as I think it raises an important point about how we define “optimisation” in engineering design.
I agree that, if a lighting system can be reduced while continuously meeting all the relevant design requirements, then it would make sense to do so regardless of the carbon intensity of the electricity at that particular moment, however, I think there is another aspect worth considering.
Cost is inevitably one of the fundamental factors in engineering design, as designers have to work within the client’s requirement and project budget, and therefore I would not necessarily describe a system that was not designed with future carbon considerations in mind as a failure on the part of the original engineers, since they may have made a perfectly reasonable decision based on the requirements and priorities that existed at the time, although it is worth acknowledging that some countries are now introducing increasingly stringent regulations requiring carbon emissions and environmental impact to be considered in building design, which means that the priorities and requirements influencing engineering decisions are also evolving.
However, the challenge I am trying to raise is whether financial cost should remain the only significant optimisation criterion when the long-term environmental cost of carbon emissions is becoming increasingly important, as a solution can be financially more expensive or less energy-efficient in a conventional sense, yet still be considered worthwhile when its contribution to decarbonisation is taken into account.
Green hydrogen is a good example, as producing green hydrogen is currently relatively expensive and the overall energy pathway involves significant conversion losses when renewable electricity is converted into hydrogen and subsequently converted back into useful energy, which from a simple energy-efficiency or short-term cost perspective can make the process difficult to justify in many applications, nevertheless, substantial investment is being made in green hydrogen because the objective is not simply to minimise the immediate cost or maximise energy efficiency, but also to reduce carbon emissions and develop alternatives for sectors where direct electrification is difficult.
I see a similar question emerging in buildings, as perhaps the objective should not simply be “What is the lowest-cost or lowest-energy lighting system?”, but rather “What is the lowest-carbon solution that remains technically, economically and operationally viable?”
This is where my original question about carbon-aware lighting comes from, as I am interested in whether, after conventional lighting optimisation has already been applied, there could still be additional opportunities to reduce operational carbon by considering factors such as renewable-energy availability and electricity carbon intensity.
Of course, this would need to be justified quantitatively, as the additional carbon reduction would have to be significant enough to justify the additional cost and complexity of the control system. So I completely agree that cost-effectiveness must remain an important consideration, however, my question is whether, in the context of net-zero buildings, we should broaden the definition of optimisation to include the long-term environmental cost of carbon emissions, rather than considering financial cost and energy consumption alone.
I appreciate your comment because it highlights an important question that I think needs to be addressed before this idea can be developed further.

DShutt said:

If as you propose, lighting could be "optimised" (and I think you actually mean reduced) in response to high carbon generation then why shouldn't that optimisation persist continually, saving energy (and thus money and carbon) all the time?

That was exactly my first thought - or to frame is slightly differently, if you have an excess of low carbon electricity available locally, why not export it and suppress the generation by higher carbon grid generators? (rather than "waste it" producing light that wasn't really needed after all.) After all the big picture is global emissions, not just what can be attributed to just your one building.

Now if you wanted to support renewable generation by creating a load when the overall grid had an excess of renewables, that would be a different matter (although in that case, storage is probably a better option).

   - Andy.

Hi,

Unless there is significant embodied carbon in the lighting equipment itself (is there, I haven't investigated?) then energy consumption and carbon emissions are proportional.(although I accept that that proportionality might vary over time).  Any reduction in energy use therefore reduces carbon emissions and should be implemented on a continual basis.  I don't see how having a more complex control system will help here.

I would also note that more complex control arrangements will have their own carbon cost and might also have the effect of turning lighting into a subscription service (where is the carbon intensity data and associated comms coming from?) which is just ridiculous!

I do accept that the priorities given to energy efficiency (whether driven by energy cost, carbon emissions, light pollution issues or something else) might change the extent to which lighting systems might be optimised but I really can't see why we need to vary that optimisation in near real time in response to the generation mix.

I broadly agree, but there is a counter argument if you consider that the lighting requirements in many buildings, includes a significant proportion of what might be classed as discretionary, or luxury lighting, that goes beyond the minimum required for basic health and safety and functional purposes.

That additional lighting, beyond the basic minimum, does or could have some response to carbon-intensity, or price, for example from time of use electricity tariffs. The tricky question would be the value of that additional lighting, to determine and when and how much response there should be to price/carbon. 

But overall, given the now relatively low energy usage requirements of lighting as compared to space heating, I was thinking you might have more impact on carbon not by adjusting light levels, but through possible psychological effects of colour temperatures, by adjusting light colours. Can changing light colour reduce the need for heating or cooling, would shifting the lighting colour temps on a cold day, allow you to run at a lower building temperature and reduce your heating demand? Would the reverse work during high temperatures - more blue lighting and less building cooling.

Betteridge's law of headlines: "Any headline that ends in a question mark can be answered by the word no." 

If there's part of the building that doesn't need bright lighting, then it doesn't need bright lighting whether it's sunny outside or not. If turning down the lights means that you start exporting electricity, then for that time you are carbon-negative. Which makes up for the cloudy days when you are carbon-positive.

If your building has windows, then you probably should do the opposite - turn the lighting down on sunny days.

Of course, the goal may be greenwashing. Make it sound like you're being eco-friendly by turning down the lights when your solar panels are generating less.

The optimisation could well be for maximum visibility for hazards at a distance, the over-illuminated workplace syndrome. Some street lighting is over bright to give an illusion of safety, rather then being sufficient to avoid stumbles in the dark. 

In large complexes, one can find that all one sees are lots of lights, rather than the plant it's meant to illuminate. The illumination levels assume a nice uniform illumination, like a cloudy sky, which isn't what we actually get.

It could be many scales of mood lighting, or colour matched sales isles, all of which could be optimised in wonderful ways, especially if there is a pricing incentive behind a "peak carbon charging" level of control. Perhaps it becomes an opt-in pricing regime that reinforces the need to eliminate the gas peaker plants. It may even be an on-site local battery peaker supply.

Simon Barker said:

If your building has windows, then you probably should do the opposite - turn the lighting down on sunny days.

Just to note that the recent historical propensity for glass skyscrapers ended up requiring more carbon use in the form of air conditioning for the greenhouses that they had built. Most needed special screens to reduce the solar loading.

It just goes to show that we also need some holistic thinking rather than the architectural fashion thinking.