Hydronic floor heating models provide predictions in estimating heat transfer rates and floor surface temperature. Information on the model performance and range of validity of its results are often lacking in literature. Researchers have to know the accuracy and robustness of the model outcomes for performing energy and climate comfort calculations. This article proposes a novel validation methodology based on the uncertainty analysis of input data/parameters of one-dimensional model of hydronic floor heating tested in a thermostatic booth simulator and compared with experimental measurements. The main results are: (1) prediction accuracy between 0.4% and 2.9% for [Formula: see text] and between 0.7% and 7.8% for [Formula: see text] when the serpentine has tube spacing (p) of 0.30 m, (2) prediction accuracy between 0.5% and 1.4% for [Formula: see text] and between 8.7% and 12.9% for [Formula: see text] with p = 0.15 m and (3) [Formula: see text] mostly affects predictions with oscillations between 6.2% and 2.2% for [Formula: see text]. This model provides robust and reliable predictions exclusively for [Formula: see text] when p = 0.30 m.

Plenty of technical norms, included in the EPBD umbrella, assesses the performance of buildings or its sub-systems in terms of efficiency. In particular, EN 15316 and its sub-sections determine the efficiency factors of a space heating system. This paper focuses on the estimation of efficiency factors for hydronic panel radiators. The assessment of efficiency factors occurs by evaluating the amount of heat emitted from the heat emitter and the thermal losses towards building envelope. A factor that influences the heat emitted is the location of radiator connection pipes. Connection pipes can be located on opposite side or at the same side of the radiator. To better estimate the heat emitted from the radiator with different location of connection pipes, a transient model with multiple storage elements is implemented in a commercial building simulation software and validated versus available experimental measurements. Sensitivity analysis encompasses the variations of heat losses due to the building location in different climates, the changing of the active thermal mass and the type of radiator local control. The final outcome of this paper is a practical support where designers and researchers can easily assess the efficiency factors for space heating system equipped with hydronic panel radiators of buildings located in Sweden. As main results, (i) the efficiency factor for control is higher in Northern climates (Luleå) than in Southern climates (Gothenburg), (ii) heavy-weight active thermal masses allow higher efficiency factors than light active thermal masses, and (iii) connection pipes located on the same side of the hydronic panel radiator enable higher efficiency factors than pipes located on opposite side.

Efficiency factors are here defined as the thermal energy performance indicators of the space heating. Until recently, the efficiency factors were assumed as one value for space heating located in any climate. This study addresses the problem of how the outdoor climate affects the efficiency factors of a space heating equipped with 1D model of hydronic floor heating. The findings show how the efficiency factors, computed with two numerical methods, are correlated with the solar radiation. This study highlights the paradoxes in understanding the results of efficiency factors analysis. This work suggests how to interpret and use the efficiency factors as a benchmark performance indicator.

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