Energy Savings in Greenhouses through the Use of Heat Recovery Systems

The production of greenhouse plants is one of the most intensive components in agricultural production. One of the biggest issues is winter production, due to the important energy demands for both services. The heating service is often used for the control and management of relative humidity in addition to maintaining a pre-established temperature value. Excessive values of relative humidity in indoor environments can lead to condensation phenomena with a reduction in the quality of cultivation and significant losses in terms of yield. Dehumidification is generally obtained, in the current state of the art, by exchanging volumes of internal humid air with drier external air. The reduction of relative humidity is therefore associated with significant sensible heat losses. This heat must then be reintegrated, determining a considerable additional load for the system generator. In this study the energy savings achievable by means of the proper design and operation of a heat recovery unit are evaluated. A transient simulation was performed by a numerical code implementing the energy and mass balance of the indoor space. The calculation of the heat recovered allowed for determination of the annual thermal energy requirement reduction for the maintenance of proper temperature and relative humidity levels in the greenhouse.