PCMs and Solar Panels Enhance Efficiency in Educational Buildings

By Nidhi DhullReviewed by Susha Cheriyedath, M.Sc.Sep 5 2024

A recent article published in Buildings presented a case study on using phase-change materials (PCMs) on the external walls and ceiling and photovoltaic (PV) solar panels in the Department of Mechanical Engineering of Shahid Beheshti University (Tehran, Iran).

Background

Buildings account for 30-40% of global energy demand. Almost 70% of this energy is consumed for space heating, space cooling, water heating, and lighting. Simultaneously, population growth and unaffordable energy sources are international issues requiring better energy efficiency.

Among different passive storage methods currently used to save energy, PCMs are gaining popularity. They are used in several industries, such as transportation, construction, pharmaceuticals, clothing, etc., as they can store both sensible and latent heat.

With an increasing ambient temperature, PCMs gradually melt at their melting point. Alternatively, they release the thermally stored energy into the environment and solidify it as the temperature decreases. 

Most educational buildings in Iran are old, and their energy efficiency is low. Thus, they require sustainable passive solutions. Accordingly, this study examined using PCMs in one such building in conjunction with PV panels for energy saving and decarbonization.

Methods

This case study was performed on a building located in Tehran, a hot and dry region. Seven scenarios apart from a reference scenario (building without PCMs and PV solar panels) were considered, and their impact on the heating/cooling load and CO₂ emissions was investigated.

Scenarios 1-3 considered using PCMs on walls, ceilings, and wall ceilings, while scenario four was related to the initial building (without PCMs) but furnished with PV panels on the roof. Additionally, scenarios 5-7 combined PV panels with scenarios 1-3 (comprising PCMs).

DesignBuilder (DsB) software was used to model the considered building and simulate the above scenarios. The shading effect of PV panels on the roof on energy absorption or release by PCMs was examined for scenarios 5-7.

Macro-encapsulated layered PCMs were modeled on the wall and ceiling of the considered building to simulate scenarios 1-3 and 5-7. The coefficient of heat transfer of the used material was ensured to be within the limits defined by the Iranian code of practice.

People inside the buildings were scheduled to attend from 7 a.m. to 8 p.m., and turning on/off the heating/cooling equipment was scheduled from 5 a.m. to 7 p.m. Additionally, the appropriate temperatures for the hot and cold were set at 23 °C and 20 °C, respectively.

The monthly output data from the DsB simulation results were compared with the building's actual measured electricity and gas consumption in a year, which was available on the Gas and Electricity Distribution Company's website.

Results and Discussion

The reference scenario revealed the building’s high energy consumption. Due to the hot climate and a lack of shading devices on the window system, the cooling demand was considerably larger than the heating load. Additionally, the predicted CO₂ emissions were about 267.66 tons/year.

Adding PCMs on the walls (scenario 1), ceilings (scenario 2), and both ceilings-walls (scenario 3) effectively reduced the energy consumption; Scenario 3 had the maximum effect on lowering the heating load.

Additionally, placing PCMs on the ceiling was more effective than the wall as the former had better thermal energy exchange potential. Moreover, installing PCMs could reduce CO₂ emissions from the main energy sources by 9.3%.

In scenario 4, the shading of PV panels located on the roof increased the heating load by 12.6% while decreasing the cooling load by 8.6% relative to the reference scenario. Additionally, 169.29 MWh/year of energy generated by these PV panels could reduce about 41.2% of CO₂ emissions from primary non-renewable energy sources.

Adding PV panels on the roof and PCMs on the walls (scenario 5), ceiling (scenario 6), and both walls and ceiling (scenario 7) did not significantly reduce energy demand.

Alternatively, a 3.7% increase in the heating load was observed for scenario 5, attributed to the shading effect of the PV panels. However, the CO₂ reductions were significant (over 40%) in these scenarios.

Conclusion and Future Work

Overall, the researchers comprehensively assessed the relevance of PCMs and PV solar panels for energy savings and decarbonization through a case study on a higher education building. Numerical simulations of 8 different scenarios were performed and validated using annual measurements.

Using PCMs had a greater influence on the heating load than cooling, and they were more effective on ceilings than walls. However, the building’s total energy consumption remained fairly constant when using both PV panels and PCMs.

Alternatively, CO₂ emissions were reduced by about 50% with the simultaneous use of PV panels and PCMs on walls and ceilings.

The researchers plan to expand the study by considering variations related to dust accumulation, temperature, long-term degradation of PCMs, etc. Additionally, optimization algorithms and artificial intelligence could be used to optimize PCM usage and assess long-term cost-benefit ratios.

Journal Reference

Sedaghat, M., Heydari, A. H., & Santos, P. (2024). The Use of PCMs and PV Solar Panels in Higher Education Buildings Towards Energy Savings and Decarbonization: A Case Study. Buildings, 14(9), 2691. DOI: 10.3390/buildings14092691, https://www.mdpi.com/2075-5309/14/9/2691

Disclaimer: The views expressed here are those of the author expressed in their private capacity and do not necessarily represent the views of AZoM.com Limited T/A AZoNetwork the owner and operator of this website. This disclaimer forms part of the Terms and conditions of use of this website.