Predictions’ robustness of one-dimensional model of hydronic floor heating: novel validation methodology using a thermostatic booth simulator and uncertainty analysis

Abstract

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.

Paradoxes in understanding the Efficiency Factors of Space Heating

“…c) Paradoxes how would it be possible to consider the efficiency factor as a benchmark for the designing of the space heating by dissolving the paradoxes on this topic? To study how the solar radiation and the geographic location affect the efficiency factors, a room model equipped with 1D model of hydronic floor heating system (validated in Brembilla et al (2018)) was developed with the building energy simulation BES software IDA ICE vers. 4.7.1.…”

“…The answer to such question is to seek in the accuracy of the numerical model used to compute the heat transfer rates/losses. A recent study, see Brembilla et al (2018), validated the 1D model of hydronic floor heating (used in the current paper) developing an innovative validation methodology. The study applied the validation technique developed in Lomas (1991) (recently applied in Strachan et al (2016)) at the model predictions obtained in a booth simulator.…”

“…IDA is a variable time step solver based on systems of differential algebraic equations as described in Balocco et al (2015), Rohdin and Moshfegh (2007). As mentioned in Brembilla et al (2018), by trying smaller time step, the accuracy of the model predictions remain unchanged for the significant digits considered in estimating the accuracy oḟ q up and T f . The latter consideration confirms that the efficiency factors can be predicted exclusively during the design phase of the space heating.…”

The impact of control strategies on space heating system efficiency in low-energy buildings

“…Differential sensitivity analysis identifies the variation in the model outcomes when the input data/parameters vary one at a time subjected to a perturbation of AE1% around its base value as explained in Munaretto et al 35 A calibration process of the space heating model took place since the observations lay outside the predictions' uncertainty bands. The methodology proposed followed the suggestions in Brembilla et al 36 and Macdonald et al 37 The calibration process consisted of shifting the internal loads (electrical appliances, lighting and occupancy) by adjusting their intensity systematically. By doing this, the intensity of each internal load was adjusted by AE1% around its base value.…”

“…As second step, the internal loads were shifted by AE1 hour in respect of their base schedule as mentioned in Reddy et al 38 In addition to varying the internal loads, the outdoor temperature varied by AE1% around its base value. 36 The calibrated model was chosen from the results that best matched the data measured.…”