Integrated solar water and air heating: A control-based study for thermally active buildings
Bibliographic record
Abstract
• This study is the first to combine air and water solar heaters for radiant floors. • A novel hybrid control links air and hydronic loops for faster thermal response. • Control tuning cuts heating costs by 33–45% compared to gas or single-mode systems. • Optimized control keeps discomfort hours below 3% without raising operating costs. This study investigates a hybrid solar-assisted heating system that combines flat plate water heaters and unglazed air heaters to serve thermally active buildings in cold-humid climates. The work addresses two key limitations in conventional solar-radiant systems: the slow thermal response of radiant floors and the lack of attention to ventilation-side heating. A dynamic model was developed in TRNSYS for an office building, incorporating detailed control logic and realistic occupancy, ventilation, and weather conditions. Unlike past studies that focused only on collector performance or used simplified demand profiles, this work integrates both hydronic and air loops and comprehensively evaluates indoor thermal comfort metrics. Parametric simulations and Latin hypercube sampling were used to construct a Cost–Discomfort Pareto frontier to identify optimal control settings. The proposed system achieved a high solar fraction (0.83), low operating costs (19.87 CAD/month), and a discomfort rate of only 6.62%. Compared to single-mode systems, it reduces monthly costs by up to 43% and unmet comfort hours by over 60%. Fine-tuned control settings further cut costs and discomfort by 5.87% and 56.65%, respectively. Lifecycle cost analysis showed that the proposed system reduces the levelized cost of heat by 2.95 times, compared to a conventional gas boiler system, while reducing the percentage of unmet hours by 16.9%. The system’s simultaneous delivery of hot air and water, as well as tailored control, offers a practical solution for improving comfort and reducing costs in low-energy buildings. These findings are especially useful for system designers aiming to maximize the effectiveness of solar heating in cold climates.
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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".