Keeping Roadside Cabinets Cool During Heatwaves
At the beginning of September, we were fortunate enough to enjoy a second summer as temperatures soared and the sun beat down. Many took advantage of the opportunity to socialise outdoors, walk in the countryside, and perhaps enjoy a cheeky pint. For roadside cabinets, however, the higher temperatures are harsh and can cause temperature sensitive equipment to trip or malfunction.
At Ritherdon, we pride ourselves on identifying new development opportunities through carrying out trials and gathering data. We have created a number of testing cabinets that we use to trial different configurations of ventilation in an attempt to find the best way to ensure our cabinets stay cool during the summer.
On this occasion, we performed a series of experiments using two RB Cabinets and chose the RB1250 size with double doors. In each cabinet we placed six thermocouples on the backboard that we used to measure the temperature at various positions. We also measured the ambient temperature outside the cabinet for comparison.
Both roadside cabinets were ventilated using our standard method – an exhaust fan at either side of the top of the cabinet and a bank of louvres for inlet flow at the bottom of either side. RB Cabinets come with vents as standard.
Analysing the data gathered from these test cabinets revealed two interesting points to consider:
The Impact of Cabinet Colour on Internal Temperature
We tested two cabinets, one black and one light grey. The colour black absorbs radiation, whereas lighter colours tend to reflect radiation.
As a result, we saw much higher temperatures in the black cabinet than in the light grey cabinet – at the hottest point of the day the temperature varied by as much as 8 degrees!
Temperature Variation within the Cabinet
Air that is hot will rise above air that is cool in a phenomenon known as convection, and the same holds true within our roadside cabinets.
What we found interesting was the degree to which the temperature varied between the bottom of the cabinet and the top of the cabinet.
On cooler days or at night, this difference is less pronounced, however during the hotter days we found that the temperature of the lower half of the cabinet to be on average 20 degrees lower than the top half.
Final Recommendations
In recent years, the UK has experienced hotter summers than ever and even thought this year seemed like an exception, extreme weather events like the late heatwave we experienced this September are becoming increasingly likely.
In fact, the MET office predicts that by 2070, hot summers will be between 4 and 7 degrees warmer. Based on this and the findings above, we would recommend that any temperature sensitive equipment be placed within lighter coloured cabinets and lower down on the cabinet backboard to ensure that it can run smoothly during hot summers and unexpected heatwaves.
Further Reading:
September 2023 Late Summer Heatwave Report from the Met Office.
How harsh temperatures affected cabinets in the UK during the Summer of 2022 Engineers with Umbrellas Protect UK Broadband Cabinets from Heat ISPreview UK
