Zoning comfort and energy efficiency report
Airzone proposes that the suitability of a zoning system should be evaluated from the point of view of the occupants’ thermal comfort, heating/cooling power provided and annual electrical consumption, when compared with an un-zoned inverter system.
At present there is no tool for calculating the savings that an inverter system with zoning and without bypass can achieve in comparison to an inverter without zoning. This study was carried out by considering a system, with detailed formulae for the heat transfer mechanisms in buildings, to which an inverter air conditioning system is coupled, in order to simulate actual operating conditions.
Graphs 1 and 2 show the percentages of thermal comfort achieved by each system when operating in Madrid. This comparison has been established between an un-zoned inverter system and an inverter system with integrated zoning, but does not take into account any energy management algorithm, which modify the temperature settings with the aim of reducing electrical consumption.
The time periods for which the system was in cooling mode have been differentiated from when it was heating. In this study of thermal comfort, the hours for which the inverter system was turned off have not been taken into account.
Graph 3 shows the annual electricity savings results for zoned systems with integration, with and without temperature limitation control strategy, Blueface, when compared with an un-zoned inverter system.:
1. Choosing an inverter system with integrated zoning in comparison with an un-zoned inverter will result in a reduction in the thermal energy to be removed and, therefore, the option of selecting a unit with a lower thermal power rating. This reduces the initial cost of the investment in the air conditioning unit.
2. The Zoned inverter system with integration and without bypass provides annual electricity savings of between 1.7% and 4.5%, when compared with the same system with bypass. The inverter system with integrated zoning and without bypass provides annual electricity savings of between 17% and 32% when compared with an un-zoned inverter system. This reduction in annual electrical consumption is due to the reduction in the energy contributed by the unit and the increase in the number of hours for which the unit is working in the inverter mode.
3. The Zoned inverter System with integration can maintain a level of thermal comfort of over 90% in all the zones. The un-zoned inverter system can only maintain these levels in the control zone.
4. The Zoned inverter system with Blueface gateway provides annual electricity savings of between 41% and 53%, when compared with a non-inverter system, and of between 28% and 30% when compared with a Zoned system with integration.
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