Key outcomes:

  • Energy consumption reduced
  • Internal thermal gradients minimised
  • Maintenance procedures simplified

Around 40% of a commercial building's energy usage results from Heating, Ventilation and Air Conditioning (HVAC) [1]. For commercial landlords, the figure is event bigger, with HVAC accounting for around 70% of the base load (i.e. energy usage discounting tenants’ computers, hardware etc.).  With numbers like these, energy efficient cooling can make a big difference to ongoing operational costs, and also provide an environmentally responsible facility.

Temperature distribution inside the thermal storage tank under worst case conditions.

Figure 1: Predicted thermal distibution with the storage tank during extreme weather condtions.

In this project Synergetics was tasked with modelling and optimising a thermal storage tank designed to shift the cooling electrical demands from using high cost peak electricity to cheaper off peak loads. The key idea was to run a chiller overnight, and store the cold water in large tank, which could then be used to cool building air flows during the day. A storage tank like this will inevitably incur some losses, but good design optimisation can minimise this, and improve chiller efficiency by running the chiller during cooler night time hours. The optimal solution involved balancing the desire to minimise internal mixing which creates strong thermal gradients within the tank, with finding a design that leads to easy maintenance. This configuration allows the client to run chillers overnight, with minimal storage losses, significantly reducing electrical bills, whilst still providing a comfortable workplace.

[1] Guide to Best Practice Maintenance & Operation of HVAC Systems for Energy Efficiency, AIRAH, January 2012