The HVAC industry finds itself in a slightly difficult position in terms of summer heatwaves. The world appears to be getting warmer, so more people want air conditioning, which is often seen as bad for the environment, causing the world to get warmer. How does the industry square this circle?
The International Energy Agency (IEA) has issued a report called “The Future of Cooling”. It predicts that the use of air conditioning globally will triple by the year 2050, due to rising incomes in China, India and South East Asia. That puts aircon right up there with bitcoin mining, in terms of energy demand.
Dr Fatih Birol, of the IEA, has described the increasing demand for air conditioning as a “blind spot” in the environmental debate. Interestingly, aircon units bought in Europe and Japan are on average 25% more efficient than the ones sold in China and the US. So to begin with, a move to better performance would have a significant effect and represents an easy win.
The real answer however, must lie in new technology. Some of the ideas being discussed are, to put it mildly, interesting.
HVAC meets Star Wars
For example, it seems that researchers at Stanford University have been looking into “cosmic cooling”. This takes the familiar HVAC idea of venting hot air to the outside atmosphere, to its ultimate conclusion. The concept is based around vacuum chambers. These will be designed to remove heat from the air, by drawing it inside the chambers. Then, in a planetary version of an HVAC system, they will beam the hot air into space.
There’s also research going on into radiative sky cooling, which the researchers think could cool a house by 20%, without using any energy at all. It works exactly like a solar panel, only in reverse, with panels on a rooftop exuding heat from the house. Rather like early solar panels, the method was previously limited by the weather. The infrared thermal energy could only exit via the panels on clear, dry nights, and most people want cool air during the hottest part of the day.
But newer versions of the technology use fluids that get round this problem and are able to reflect the heat back out into space, using space as a kind of heat sink.
Water flowing through the panels can be cooled to 5 degrees below the outside temperature. Models demonstrated that in a commercial HVAC system, if the panels were installed downstream from the condenser, they could achieve a temperature drop of over 20%. The panels use acrylic walls and have polystyrene insulation and covers, with the water flowing through a plate heat exchanger.
Of course, Stanford is in California, and the researchers’ model used the kind of climate encountered in places such as Las Vegas. Here in the UK, at the height of any heatwave, HVAC engineers know that they are only weeks away from a sudden cold snap and complaints from users about their building not being warm enough.
The variability of our climate is a massive challenge for the people who have to provide a “thermally comfortable” working environment, so every new idea is worth a look.