Abstract

Solaria and greenhouses may provide many benefits, such as collecting solar heat and providing an environment where people and plants can thrive. The aim of this work is to enhance the solar energy utilization in solaria and greenhouses by improving the design and control of their fenestration and thermal energy storage (TES) systems.

This work is focusing on two aspects: first, to maximize the solar radiation collection, and secondly, to make effective use of the collected heat by designing appropriate TES systems. These two aspects are inherently linked and must be considered together, since improving only one of them in isolation cannot satisfactorily improve the overall performance.

Designing energy efficient fenestration systems in heating dominated climates calls for a high solar transmittance and thermal resistance. However, increasing the thermal resistance generally happens to the detriment of the solar transmittance, which complicates the design process. To address this issue, a methodology has been developed, which allows the comparison of different fenestration systems (including exterior and/or interior shades) on a diagram that shows their annual net energy gains for a given façade and climate.

A new strategy for improving the control of shades has been developed, based on maximizing the total heat flow through fenestration systems. This control algorithm was shown to reduce heating requirements and improve thermal comfort. By following the proposed methodology and control method for fenestration systems, the indoor operative temperature can be significantly increased; TES systems are thus essential for reducing temperature fluctuations. The design of passive TES systems in solaria and greenhouses has been studied with two complementary modelling approaches: frequency response (FR) and finite difference (FD). The FR model is used during typical short design periods for analyzing the TES sensitivity to different design variables. The FD model is used for annual performance evaluation using real weather data for two Canadian cities and years. A methodology based on the FR model is proposed and design recommendations are provided. If was found that increasing the TES thickness from 0.1 m to 1 m can raise the minimum operative temperature by 3 to 5 °C in unheated solaria and it is recommended to select a TES with a minimal thickness of 0.2 m for reducing temperature swings.