Mar 3

Energy efficient HVAC systems for maintenance microclimate

  • March 3, 2016
Energy efficient HVAC systems for maintenance microclimate

During the second half of 2015 TANGRA completed the installations of Abrites OOD’s administrative and production building in Sofia. The production plant will be specialized in the assembling of electronic modules.

The design and building assignment involved heating, ventilation and air-conditioning systems for production section, offices and auxiliary premises. The main task of the design process was to achieve conformity with the regulatory requirements for microclimate, while maintaining the optimum capital investments/energy costs ratio.


The following chart provides a general idea of the “philosophy” of the optimization:
 microclimate-chart 1. Installation with low capital investment and higher energy costs.2. Installation with a higher capital investment and low energy costs.

2. The shaded area shows the savings, resulting from the proper investment decision.

The objective, set by the investor, was achieved by working in several directions:

– The heating and cooling of the premises is provided by Hitachi’s VRF – variable refrigerant flow system. Hitachi VRF system ensures high transformation ratio, i.e. high received/utilized power ratio (СОР – in winter mode/ЕЕR –in summer mode).






The ventilation is provided by high efficiency heat recovery ventilation systems, recovering up to 88% of the energy of the discharged air. These systems were manufactured by “TANGRA” and form part of the TANGRA EVB HiE series.


The utilization of the heat from the technological processes in the air conditioning and ventilation systems significantly decreases the energy consumption during winter.

The free cooling, used in the transitive periods, replaces a part of the cooling power of the system. This also reduces the cooling costs.

Heat recovery ventilation systems control is performed by TANGRA Smart. This system provides information on the status of the machines, the status of filters and the functioning of the additional equipment. The most significant and innovative function is the visualization of the current levels of energy saved by recuperation. It visualizes percentage of saved energy per hour.


In conclusion, it should be noted that the systems, developed and implemented by TANGRA fully meet the energy efficiency requirements of Commission Regulation (EU) No. 1253/2014. They will continue to meet even the increased parameters of this Regulation after 01.01.2018. This means that the heat recovery efficiency is more than 75%.

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