Smart building materials company ClearVue Technologies provides an update on the progress of its solar greenhouse trial at Murdoch University and the progress of the installation of a commercial solar greenhouse in Japan.
Energy production performance and energy efficiency of ClearVue's PV glazing at Murdoch University Greenhouse have been measured continuously since the greenhouse officially opened on 19 April 2021.
The greenhouse comprises four glazed rooms and an enclosed, unglazed preparation room at the rear (south). The four rooms include one with normal glazing to create a scientific 'control' as a baseline from which to measure the performance of the ClearVue glazing against a traditional glazed greenhouse.
The remaining three rooms of the greenhouse comprise three different versions of the ClearVue PV solar glazing technology. The second room uses the current commercially available ClearVue glazing product while the third and fourth rooms are variants of that product using different amounts of nano- and micro-particles to look at optimization of power generation and impact on plant growth dynamics.
Stages of the trial
To conduct the energy efficiency and power performance trials, ClearVue's own in-house technical team managed the data collection.
To conduct the plant science research, ClearVue engaged with Murdoch University's Professor Chengdao Li, a molecular geneticist, and his team including Dr. Hao Luo under a collaborative research agreement.
Prof Li's team looked at agronomic and physiological characteristics that were recorded from germination to harvest, to understand the plant response to the filtered light through ClearVue's solar glazing panels.
In this context, certain plants need at least some ultraviolet (UV), whilst others perform better with little to none. Other plants need different levels of visible light transmission. The aim of the Stage 1 winter plant science trial (see below) was to commence investigation into finding the right balance for an optimum growing environment whilst maximizing power generation and energy savings.
As expected, different plants had different responses to the light passing through the solar glazing panels at different growth stages, where a significant amount of UV and infrared (IR) were removed by virtue of the operation of the solar glazing using those wavelengths for power generation.
For the purposes of the three elements of the experiment, the ClearVue greenhouse incorporates a range of sensors that record and present an array of data in real time providing the scientists with accurate information relating to conditions like temperature, humidity and the actual amount of light in all wavelengths that the plants were receiving.
This information was analyzed to make automatic adjustments to lighting, heating, cooling, louvres, fans, blinds, and reticulation systems, which in turn allowed scientists to maintain a constant microclimate to provide optimum growing conditions - a proportion of which is being powered by the energy generated by the ClearVue glass deployed on the greenhouse itself.
The four rooms of the greenhouse have been divided up with the use of insulated expanded polystyrene (or EPS) refrigeration type paneling and the two East and West ends of the greenhouse were blocked off with EPS to achieve (as close as possible) four consistent rooms for experimentation.
The impact of this on the overall experiment for all rooms is a loss of some light (in all wavelengths) entering the greenhouse - a normal commercial growing greenhouse (for example, the solar greenhouse under construction in Japan - see below) would have no such internal barriers to light entry and solar traversal across the greenhouse.
This important limitation was understood at the outset of the trial and could only have been overcome by the construction of four separate adjacent greenhouses or by using clear room dividers made of polycarbonate or plain glass which would have been less reliable for data collection purposes and also allowed more natural light in that's capable of reaching the plants, thereby generating a less accurate measurement of the energy efficiency savings offered by the ClearVue product.
Additionally, it should be noted that the greenhouse is a research greenhouse and the rear (Southern side) of the greenhouse has an unglazed scientific preparation room running behind all four growing rooms, meaning there is no light is coming from that side - whereas in a regular commercial greenhouse this would not normally be the case and all sides of the structure would be glazed permitting maximum daylighting.
Another influence on accurate data collection was that louver operation was impaired in all rooms during the course of the trial with three rooms staying closed and one room staying open. Repairs and maintenance have been completed on these in advance of the Stage 2 trials.
A focus of the trials is to measure the energy efficiency and power savings offered by the ClearVue glazing and the power generated from the glazing. This focus has led to careful monitoring and control of the air-conditioning and fans in each of the greenhouse rooms leading to automated shut off of those systems where cooling or heating is not needed to maximize overall energy savings. This approach, although logical, ignores the importance of internal air circulation within a closed greenhouse environment. Air circulation is critical in a greenhouse for plant pollination where there are no natural insect pollinators.
Read the complete research here.
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