ACES Overview

Air Conditioning Energy Saver

Air Conditioning Energy Saver

In many buildings air-conditioning systems can be the biggest consumers of energy putting considerable demands on the local and national grid during the hottest days of the year.

ACES is a range of air conditioning energy saving products that have been designed to significantly reduce energy running costs while maintaining, and often improving comfort levels. Their primary applications are found in the commercial sector and larger private housing.

The Problem

The primary purpose of an air conditioning system is to provide force-cooled air to firstly reduce and then maintain internal building temperatures to an acceptable predetermined comfort level.

Air conditioning systems are normally switched on or off automatically in a series of cycles via a time clock or room thermostat, more often these days combined within a simple programmer.

Typically both the compressor and fan within an air-conditioning system will run continuously until the room thermostat is satisfied. During this period the compressor consumes most of the energy, with the fan using a negligible amount by comparison.

However, air-conditioning systems are routinely designed and specified to cope with the hottest days of the year – and then uprated somewhat to the next available size. This means that many air-conditioning systems are designed to operate under conditions they will rarely, if ever, encounter.

Throughout the cooling cycle the compressor will provide cooling to the coils within the duct and the fan will extract ‘warm’ air from the room. As it passes across the cooling coils it loses its heat and the heat is subsequently expelled from the building.

It is widely recognised that as cooling begins to take effect in the room, the temperature of the air entering the duct falls and the differential in temperature between the air entering and leaving the system narrows and a threshold known as “thermodynamic saturation” is achieved. This is the stall point at which the air leaving the system is no longer benefiting from the aggressive cooling and yet the compressor will still needlessly continue to run, flat out!

Does this mean that there are significant periods of time during each duty cycle when the compressor is running without any beneficial effect on the room temperature? Yes, almost certainly!

Also, even when the motor is running and providing effective cooling into the building it may still be using more energy than it needs to because the load profile of the motor is such that it requires significantly more energy in the first few minutes following start-up than it will for the remainder of the cycle. However, the motor has no intelligent way of adjusting the amount of energy it draws during each phase of the cycle. All of this contributes to a motor and compressor that is oversized by design and uses more energy than is needs to under ‘normal’ operating conditions.

Single speed ac induction motor driven compressors are engineered so as to be able to firstly start the cooling cycle and build up the suction gas pressure and overcome any initial inertia (which can be a heavy initial load), and thereafter simply maintain the momentum during the remainder of the cycle. Significantly, compressor motors will use almost the same amount of energy for the whole of the cooling period, regardless of the fact that by measuring motor torque it is evident that the load demand varies dramatically during the duty cycle.

Does this mean that for most of the time when the compressor is needed to run it is also drawing more energy than is really needed to complete the job of work? In almost all cases yes… compressors often run when they don’t need to and when they do run they invariably use more energy than they really need!

The Solution

Based on thirty years experience with sophisticated temperature sensing modules and intelligent motor control, MOST have developed a range of air conditioning energy savers (ACES) that specifically address both of these problems in a unique and holistic way.

ACES can deliver significantly reduced energy costs and at the same time even improve levels of comfort. We have combined both the features of intelligent temperature sensing with microprocessor based self learning control algorithms that constantly monitor the temperature of the air passing across the cooling coils, alongside dynamic motor optimization and control.

With ACES we can now identify the exact stall point at which thermodynamic saturation is reached and switch the compressor off while keeping the fan running so as to extract as much latent ‘free’ cooling as possible from the coils, without compromising any cooling effect in the room.

Furthermore, by providing dynamic control of the compressor motor while it is running we can ensure that the compressor uses only the minimum amount of energy it requires during each phase of the duty cycle… Initially we soft–start the motor, and then deliver full power to match the higher demand and thereafter gradually ease back on the energy being drawn. We give the motor the exact amount of power it needs at any instance of time.

The ACES range of Air Conditioning Energy Savers will:-

  • Save up to 35% in energy costs
  • Provide more effective comfort cooling
  • Reduce heat, noise and vibration within the compressor
  • Reduce maintenance costs
  • Extend equipment life

The Next Generation

BEST are currently developing a range of products and solutions that combine into an “Eco-system”. This is a range of load side energy saving products that are connected to an Eniscope Hybrid Real Time Energy Management System, thereby providing remote web-enabled monitoring of individual items. This means we will be able to automatically identify energy leaks at a granular level.

The new ACES Hybrid will combine the benefits of an intelligent temperature sensing module and dynamic motor control into one unique product. This innovative solution is a world-first and is therefore subject to patent applications and both trademark and copyright design protection.

In addition ACES Hybrid will also communicate to the World Wide Web via Eniscope in real time on important matters like; Compressor run time, equipment efficiency and specific itemized energy demands and running costs. Information will be archived in a cloud-based system – 24/7/365 – and any combination of salient reports can be accessed and provided at site level to provide optimum management and control of all the energy used in the building.