The lights are on — but is anybody home?
The two photos below are of Perth CBD. The top photo was taken on a weekday evening in July 2008 at about 8pm in the evening. The photo below was taken a few days later on a Sunday night at pretty much the same time. *
So why is it that Perth’s office buildings are lit up like a Christmas tree on a weekday evening but not at the weekend? Some some crude estimates (based on counting office floors that are lit) suggest that 60% fewer lights are left on over a weekend evening than at the same time during the week.
I think it’s safe to say that it isn’t because Perth’s offices are full of hard working employees at 8pm on a weekday evening. Sure, there’ll be a few folk burning the midnight oil but most of this lighting is going to waste.
Let’s try and work out what this equates to in terms of CO2 emissions. We’ll pick on Central Park as it’s the tallest building on Perth’s skyline. In an earlier post we estimated Central Park’s emissions at around 16,000 tonnes CO2e per year
Now we know that lighting is responsible for around 21% of electricty consumption in commercial offices. Based on that we can estimate that lighting in Central Park generates around 3,200 tonnes CO2e per year or an average 9 tonnes per day. Down at this level it becomes clear that leaving lights burning unnecessarily, even for only an extra hour or two every day, can in itself be a significant cause emissions.
So what can we do about it?
There are only two ways that lights get turned off — either it’s the last person to leave the office at night or the building management system (BMS) does it for us. Certainly for larger office buildings like Central Park a BMS will be controlling many aspects of the office environment. Making sure that your BMS is configured correctly and reminding staff of the importance of turning out lights when they go home at night are easy and very cost effective ways to reduce the emissions generated by your office space.
* It’s worth noting that these photos were taken after the explosion at Apache Energy’s Varanus facility which lead to a significant energy shortage in Western Australia. Most office buildings in Perth were supposedly doing everything they could to reduce their power consumption. Even the neon advertising on the tops of the buildings had been turned off!
