Assessing the Energy Impact of Different Strategies of Integrating PV/Thermal Heat Recovery Systems in Scottish Homes
Bibliographic record
Abstract
The research on photovoltaic thermal (PV/T) solar systems has been on the rise. In 2005, the International Energy Agency (IEA) Solar Heating and Cooling (SHC) programme launched the 1st Task 35 experts meeting to initiate international collaboration on PV/T solar systems. Following the end of the Task 35 research activities, SHC and the Energy Conservation in Buildings and Community Systems (ECBCS) formed a Task 40/Annex 52 joint programme and commenced collaboration on net zero energy solar buildings. Their studies encompass the scrutiny of exemplary net zero energy solar building projects selected from each participating country. Canada’s first net zero energy home, called Écoterra house, built in 2007 through the federal government’s sustainable housing initiative, and the United Kingdom’s Z-en house are currently amongst them. Both projects have been aimed at demonstrating PV/T systems for space heating in addition to power generation. This feasibility study was initiated in order to lead Scottish Z-en house builder, ROBERTRYAN Homes, to thorough understanding of basic features and potential performance of a PV/T HR system under Scottish climatic conditions and further explore how the system can effectively be integrated with the Z-en house to be constructed in 2012/13. The house is being designed to circulate PV heated air throughout the interior via a mechanical ventilation heat recovery system—i.e. implementation of a PV/T MVHR system. In this study, the heat generating capacity of low efficient PV cells (amorphous silicon) and the high efficient counterparts (poly-crystalline) was analysed using the energy and environment simulation tool called EESLISM which was invented in 1989 by Prof. Mitsuhiro Udagawa, Kogakuin University, Japan. The air flow assisted by the MVHR system was assumed to be 300m3/h, 432m3/h or 864m3/h and the velocity of 0.45m/s, 0.5m/s or 1m/s, respectively. The fresh air is drawn under a 7% or 14% efficient PV roof whose module coverage is set according to the nominal power output of either 4kWp or 8kWp. This study confirmed that PV generates heat which makes the fresh air running under the PV roof 10-15˚C warmer than the outside temperature even during the Scottish winter. Low efficient amorphous silicon PV generates more heat than high efficient PV of the same nominal power output due to the necessarily larger area of amorphous PV roof coverage as well as the less sensitivity to temperature rise as opposed to the mono/polycrystalline counterparts. In short, the ventilated PV/T integrated roof helps raise the temperature of the fresh air running under the PV panels and being extracted by an MVHR system, if both the roof and the extractor are connected physically via a duct; thus, it contributes to supplementing the indoor space heating. The architectural integration was considered as important and was visualised in the course of this study. Moreover, the air flow of the PV/T HR system was also considered as one of the key cost-effective design factors that help improve the PV/T heat collecting performance while maintaining electricity generation properties as the PV modules are cooled by the ventilation. In the 7% efficient 4kWp PV/T roof with an angle of 30˚, the EESLISM simulation indicated that the annual rate of PV/T heat collection could be increased by 77% when the ventilation air velocity is changed from 0.5m/s to 1.0m/s. The mere manipulation of the air flow is more economic and about 13 times more efficient than the increase of the PV size from 4kWp to 8kWp. Similar tendency was observed in the 14% efficient PV/T roof. However, the simulation did not extend to analysing the effect of the ventilated PV/T air velocity any more than 1m/s; thus, it may be worth continuing to investigate the extended scope in order to clarify the relationship between PV/T heat collecting capacity and the further increased ventilation rate under the Scottish climate condition in depth.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".