Here’s a slightly revised version of the famous 1930’s Irving Berlin song … “We’re having a heat wave, a Topical heat wave, the temperatures rising, it isn’t surprising”.
I say ‘topical’ rather than “tropical” because it is now almost impossible to deny that the “temperatures rising”, year on year and it really “isn’t surprising” because of man’s impact on the planet and the climate.
So as the thermometers across the country surpass 40 degrees C, how can we in the HVAC industry ensure that buildings are kept at a comfortable temperature without causing a huge spike in energy use?
Of course, heat recovery can work all year round as well
Turn it up
Most UK buildings simply aren’t prepared for the high temperatures we’ve seen this summer, but there are a number of things that building operators can to do keep both occupants and critical infrastructure safe and cool, without ramping up energy use.
The first and simplest thing, is to turn the thermostat up.
Air conditioning in the UK is often set at 21°C or lower and the temptation when it’s hot outside is to turn the thermostat down even further.
However, if it is 35°C+ outside then an internal temperature of 23°C, 24°C or higher will still feel much, much cooler and – more importantly, it will consume less energy, giving you occupant comfort without increasing bills.
Take back control
It is always worth looking at the controllers in this situation as well. If you as the commissioning or maintenance engineer make the set points slightly higher or lower, it won’t matter half as much if the occupants keep ramping the temperature up, or down.
Once they’ve had their hour-long meeting and left the room, the system will default to the much more energy efficient set point that you have programmed in.
That also means the system is running on the minimum power needed when the building is less occupied or empty.
Effective maintenance is another easy and highly beneficial way of maximising comfort and minimising energy use.
Basic things such as a visual check to ensure filters are clean and outdoor units are not blocked will allow them to work efficiently, all year round.
This is definitely something any building owner should be doing once a month or so, or more in the spring and autumn when there is more ‘debris’ from nature.
And that annual service and maintenance schedule is another way of making sure that your systems are working to their maximum while consuming the minimum of energy.
The transfer market
Many modern commercial air conditioning systems also offer the ability to maximise heat recovery.
This means that heat energy recovered from cooling spaces for occupant comfort, can be transferred to a hot water supply, or moved to parts of a building that may still need heating.
Of course, this can work all year round as well, with essential cooling needed for critical IT infrastructure producing energy that can be used to heat other parts of the building.
With modern mixed-use buildings in our towns and cities, this approach can also be used to enable heat energy from cooling gyms, offices and retail outlets to be used to provide hot water for the apartments above.
A breathe of fresh air
Finally, the clever use of natural ventilation and mechanical ventilation with heat recovery (MVHR) can also help lower peak temperatures inside buildings helping reduce the initial requirement for cooling systems – along with energy use.
Systems are available right now that can use cool nighttime temperatures to make sure a building starts the day fresh and comfortable for people.
During the heat of the day, hot fresh air can be brought down to room temperature cost effectively with MVHR able to recover about 90% of the cooling energy that would otherwise be ejected with the stale outgoing air.
As a final thought that goes beyond our HVAC industry, these levels of summer temperatures are likely in future years, so we also need to look at designing urban spaces to stop them becoming heat spots in the first place.
Things like solar shading, natural ventilation and other physical attributes like trees and green walls – can all be used to provide cooling and ventilation and help minimise the amount of energy we need to keep our cool.
Ben Bartle-Ross is a technical trainer at Mitsubishi Electric