Abstract
There exists a building energy performance gap between theoretical simulations and the actual energy usage as measured. One potential reason for this gap might be a mismatch between predicted and measured values of the heat flux q through the building envelope. There is therefore a need to develop accurate and more cost-efficient methods for measurement of q. The standard ISO 9869-1 states that, at the outdoor surface, q = ho(Ts − Tenv), where ho is the overall heat transfer coefficient, including both convective and radiative components, Tenv is the environmental temperature, and Ts is the temperature of the building surface. It has previously been shown that the sol-air thermometer (SAT) could be used for convenient measurement of Tenv under dark conditions. In the present work, two SAT units, one heated and the other unheated, were employed for accurate outdoor measurements of ho in cold winter climate. Validation was performed by comparison of results from the new method against measurements, where previously established methodology was used. With current operating conditions, the measurement uncertainty was estimated to be 3.0 and 4.4%, for ho equal to 13 and 29 Wm−2K−1, respectively. The new SAT steady-state method is more cost-effective compared to previous methodology, in that the former involves fewer input quantities (surface emissivity and infrared radiation temperature are unnecessary) to be measured, while giving the same ho results, without any sacrifice in accuracy. SAT methodology thus enables measurement of both Tenv and ho, which characterizes the building thermal environment, and supports estimation of q.
Access this chapter
Tax calculation will be finalised at checkout
Purchases are for personal use only
References
A.C. Menezes, A. Cripps, D. Bouchlaghem, R. Buswell, Predicted vs. actual energy performance of non-domestic buildings: using post-occupancy evaluation data to reduce the performance gap. Appl. Energy 97, 355–364 (2012)
P. De Wilde, The gap between predicted and measured energy performance of buildings: a framework for investigation. Autom. Constr. 41, 40–49 (2014)
ISO 9869-1, in Thermal insulation—Building elements—In-situ measurement of thermal resistance and thermal transmittance; Part 1: Heat flow meter method. 1 edn. ISO, Switzerland (2014)
M.G. Davies, The use of flux temperatures in thermal design. Build. Serv. Eng. Res. Technol. 2, 160–164 (1981)
C.O. Mackey, L.T. Wright, The sol-air thermometer—a new instrument. Trans. Am. Soc. Heat. Vent. Eng. 52, 271–282 (1946)
R.W. Muncey, T.S. Holden, The calculation of internal temperatures—a demonstration experiment. Build. Sci. 2, 191–196 (1967)
K.P. Rao, E.R. Ballantyne, Some Investigations on the Sol-Air Temperature Concept [CSIRO, Division of Building Research Technical Paper No. 27], Australia (1970)
T. Olofsson, K.E.A. Ohlsson, R. Östin, Measurement of the environmental temperature using the sol-air thermometer. Energy Procedia 132, 357–362. (2017)
N. Ito, K. Kimura, J. Oka, A field experiment study on the convective heat transfer coefficient on exterior surface of a building. ASHRAE Trans. 78, 184–191 (1972)
J. Lohrengel, R. Todtenhaupt, Wärmeleitfähigkeit, gesamtemissionsgrade und spektrale emissionsgrade der beschichtung Nextel-Velvet-Coating 811-21 (RAL 900 15 tiefschwarz matt). PTB-Mittelungen 106(4), 259–265 (1996)
K.E.A. Ohlsson, R. Östin, S. Grundberg, T. Olofsson, Dynamic model for measurement of convective heat transfer coefficient at external building surfaces. J. Build. Eng. 7, 239–245 (2016)
F.P. Incropera, D.P. DeWitt, Fundamentals of Heat and Mass Transfer, 5th edn. (Wiley, London, 2002)
JCGM 100, Evaluation of measurement data—Guide to the expression of uncertainty in measurement (GUM 1995 with minor correction). BIPM, ISO, Geneva (2008)
Acknowledgements
We gratefully acknowledge the financial support for this project from the Swedish Energy Agency, through IQ Samhällsbyggnad and the E2B2 program (project no. 39699-1), and the Kempe Foundations. We are also indebted to Fredrik Holmgren and Johan Haake for technical support in the construction of the experimental equipment.
Author information
Authors and Affiliations
Corresponding author
Editor information
Editors and Affiliations
Rights and permissions
Copyright information
© 2019 Springer Nature Switzerland AG
About this paper
Cite this paper
Ohlsson, K.E.A., Östin, R., Olofsson, T. (2019). Sol-Air Thermometer Measurement of Heat Transfer Coefficient at Building Outdoor Surfaces. In: Johansson, D., Bagge, H., Wahlström, Å. (eds) Cold Climate HVAC 2018. CCC 2018. Springer Proceedings in Energy. Springer, Cham. https://doi.org/10.1007/978-3-030-00662-4_28
Download citation
DOI: https://doi.org/10.1007/978-3-030-00662-4_28
Published:
Publisher Name: Springer, Cham
Print ISBN: 978-3-030-00661-7
Online ISBN: 978-3-030-00662-4
eBook Packages: EnergyEnergy (R0)