Open Access

ARTICLE

Experimental Study of Solar-Powered Underfloor Heating in a Defined Space

Firas Mahmood Younis^1,*, Omar Mohammad Hamdoon², Ayad Younis Abdulla¹

1 Technical College of Engineering, Duhok Polytechnic University, Duhok, 42001, Iraq
2 Engineering College, Sustainable Energy, Mosul University, Mosul, 41003, Iraq

* Corresponding Author: Firas Mahmood Younis. Email:

(This article belongs to the Special Issue: Advancements in Energy Resources and Their Processes, Systems, Materials and Policies for Affordable Energy Sustainability)

Energy Engineering 2026, 123(2), 19 https://doi.org/10.32604/ee.2025.073483

Received 18 September 2025; Accepted 05 December 2025; Issue published 27 January 2026

Abstract

This paper presents an experimental analysis of a solar-assisted powered underfloor heating system, designed primarily to boost energy efficiency and achieve reliable desired steady-state temperature in buildings. We thoroughly tested the system’s thermal and operational features by subjecting it to three distinct scenarios that mimicked diverse solar irradiance and environmental conditions. Our findings reveal a strong correlation between variations in solar input and overall system performance. The Solar Fraction (SF), our key energy efficiency metric, varied significantly across the cases, ranging from 63.1% up to 88.7%. This high reliance on renewables resulted in a substantial reduction in backup power; consequently, the auxiliary electric heater was only required to supply between 1.82 and 3.00 kWh over the test periods. The circulation pump operated on a precise control logic, engaging below 20°C and disengaging at 21°C. Crucially, the experiments verified the system’s ability not only to meet the air temperature setpoint but also to ensure the floor surface temperature stayed within required international comfort criteria. These robust results directly support the study’s main objective. For practical application, we advise increasing the total length of the embedded pipe network. This crucial adjustment would allow for a reduction in the required circulating water temperature, which in turn maximizes the utilization of low-grade solar heat and optimizes radiant heat delivery toward achieving the desired steady-state temperature. Ultimately, the study confirms that solar-assisted underfloor heating offers a technically viable, sustainable, and energy-efficient solution with the potential to significantly cut fossil fuel consumption.

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