As the temperature across the country begins to climb into prime air conditioning territory, building managers are preparing to crank up their commercial HVAC units. Because daily temperature peaks tend to coincide with daily electricity usage peaks, air conditioners put an especially heavy strain on the electrical grid. The folks at Ice Energy have a clever way to shift power needs to off-peak hours, using nothing but water and ingenuity.
The basic idea is simple — use off-peak electricity to freeze water around copper tubing containing refrigerant, insulate it very well, and release it into the HVAC system once the daytime temperature starts to rise and office workers need relief. The HVAC compressor doesn’t even need to get turned on, since the cooling is all being done by the big block of ice left over from the night before. So energy use during peak hours can fall up to 95% according to the company. (Your mileage may vary — we haven’t field tested this at TerraPass world HQ.)
Why does this matter if the building still has to use energy to make the ice in the first place?
First, the system overall uses less energy than a conventional HVAC system does for a small- to medium-sized commercial installation. Though the compressor does need to run to make the ice, making the total electricity consumed about the same as a regular system, there is up to 30% less loss in transmission off-peak (because line loss varies with the square of the current carried in the line).
Second, the shift to off-peak power consumption means that there is less stress on the electrical grid during the day, which in turns means local utilities don’t need to fire up incremental generating facilities. That in turn means lower overall carbon emissions, since those incremental facilities are often older and dirtier than base load power generation facilities are.
Third, off peak power is a whole lot cheaper, leaving building owners and tenants with extra money to spend on efficiency measures like double-paned windows and better insulation.
Ice — it’s not just for making hand-cranked margaritas anymore.