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Quasi-steady-state calculation method of temporary increased ventilation during daytime

Kim Goethals (UGent) and Arnold Janssens (UGent)
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Abstract
According to the International Energy Agency, the building sector is responsible for 40% of the final energy demand in Europe. Meanwhile, fossil-fuel energy resources are running out and the Kyoto protocol binds the governments to reduce the collective emissions of greenhouse gases. For this purpose, the European Parliament ratified the Directive on the Energy Performance of Buildings 2002/91/EC (EPBD), imposing the development of a methodology for calculating the energy performance of buildings together with minimum performance requirements. The Member States supplemented existing and new calculation methods, unfortunately, without the necessary collaboration and information exchange. In particular, calculation methods of temporary increased ventilation rates, such as opening windows, mechanical day or night ventilation, are scarce or non-existent – as shown by a preceding literature study –, despite their significant potential in reducing the cooling load and increasing the thermal comfort. Therefore, to promote the use of above-mentioned passive cooling techniques, new steady-state calculation methods should be developed and implemented in the EPBD software. As described in this paper, the authors developed a new quasi-steady-state assessment method of temporary increased mechanical ventilation during daytime – i.e. free cooling – for calculating the cooling demand and overheating risk of non-residential buildings. Based on the calculation methodology proposed in the European standard EN 13790, the impact of free cooling is calculated by a ventilation heat transfer coefficient. This parameter on its turn is determined by the air flow rate alongside a temperature adjustment factor and a time fraction of operation. The determination of the two last-mentioned factors is based on dynamic simulations of a generic small office building, using the multi-zone energy simulation program TRNSYS. Both factors are function of the monthly mean ratio of heat losses to heat gains for the case without free cooling and the maximum extra ventilation rate for free cooling. Subsequently, the method is validated based on the office building. The results show that the new calculation method introduces an – acceptable – over prediction of 10 to 15% of the yearly sensible net cooling demand compared with the dynamic simulation results. A similar conclusion can be drawn for the assessment of the overheating risk with the new method – supporting the usefulness of the new calculation method in the EPBD software.
Keywords
mechanical ventilation, temporary increased ventilation, EPBD, quasi-steady-state calculation method

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MLA
Goethals, Kim, and Arnold Janssens. “Quasi-Steady-State Calculation Method of Temporary Increased Ventilation during Daytime.” Research on Building Physics : Proceedings of the 1st Central European Symposium on Building Physics, edited by Dariusz Gawin and Tomasz Kisilewicz, Technical University of Lodz, 2010, pp. 477–84.
APA
Goethals, K., & Janssens, A. (2010). Quasi-steady-state calculation method of temporary increased ventilation during daytime. In D. Gawin & T. Kisilewicz (Eds.), Research on building physics : proceedings of the 1st Central European symposium on building physics (pp. 477–484). Lodz, Poland: Technical University of Lodz.
Chicago author-date
Goethals, Kim, and Arnold Janssens. 2010. “Quasi-Steady-State Calculation Method of Temporary Increased Ventilation during Daytime.” In Research on Building Physics : Proceedings of the 1st Central European Symposium on Building Physics, edited by Dariusz Gawin and Tomasz Kisilewicz, 477–84. Lodz, Poland: Technical University of Lodz.
Chicago author-date (all authors)
Goethals, Kim, and Arnold Janssens. 2010. “Quasi-Steady-State Calculation Method of Temporary Increased Ventilation during Daytime.” In Research on Building Physics : Proceedings of the 1st Central European Symposium on Building Physics, ed by. Dariusz Gawin and Tomasz Kisilewicz, 477–484. Lodz, Poland: Technical University of Lodz.
Vancouver
1.
Goethals K, Janssens A. Quasi-steady-state calculation method of temporary increased ventilation during daytime. In: Gawin D, Kisilewicz T, editors. Research on building physics : proceedings of the 1st Central European symposium on building physics. Lodz, Poland: Technical University of Lodz; 2010. p. 477–84.
IEEE
[1]
K. Goethals and A. Janssens, “Quasi-steady-state calculation method of temporary increased ventilation during daytime,” in Research on building physics : proceedings of the 1st Central European symposium on building physics, Cracow ; Lodz, Poland, 2010, pp. 477–484.
@inproceedings{954560,
  abstract     = {{According to the International Energy Agency, the building sector is responsible for 40% of the final energy demand in Europe. Meanwhile, fossil-fuel energy resources are running out and the Kyoto protocol binds the governments to reduce the collective emissions of greenhouse gases. For this purpose, the European Parliament ratified the Directive on the Energy Performance of Buildings 2002/91/EC (EPBD), imposing the development of a methodology for calculating the energy performance of buildings together with minimum performance requirements. The Member States supplemented existing and new calculation methods, unfortunately, without the necessary collaboration and information exchange. In particular, calculation methods of temporary increased ventilation rates, such as opening windows, mechanical day or night ventilation, are scarce or non-existent – as shown by a preceding literature study –, despite their significant potential in reducing the cooling load and increasing the thermal comfort. Therefore, to promote the use of above-mentioned passive cooling techniques, new steady-state calculation methods should be developed and implemented in the EPBD software. As described in this paper, the authors developed a new quasi-steady-state assessment method of temporary increased mechanical ventilation during daytime – i.e. free cooling – for calculating the cooling demand and overheating risk of non-residential buildings. Based on the calculation methodology proposed in the European standard EN 13790, the impact of free cooling is calculated by a ventilation heat transfer coefficient. This parameter on its turn is determined by the air flow rate alongside a temperature adjustment factor and a time fraction of operation. The determination of the two last-mentioned factors is based on dynamic simulations of a generic small office building, using the multi-zone energy simulation program TRNSYS. Both factors are function of the monthly mean ratio of heat losses to heat gains for the case without free cooling and the maximum extra ventilation rate for free cooling. Subsequently, the method is validated based on the office building. The results show that the new calculation method introduces an – acceptable – over prediction of 10 to 15% of the yearly sensible net cooling demand compared with the dynamic simulation results. A similar conclusion can be drawn for the assessment of the overheating risk with the new method – supporting the usefulness of the new calculation method in the EPBD software.}},
  author       = {{Goethals, Kim and Janssens, Arnold}},
  booktitle    = {{Research on building physics : proceedings of the 1st Central European symposium on building physics}},
  editor       = {{Gawin, Dariusz and Kisilewicz, Tomasz}},
  isbn         = {{9788372833679}},
  keywords     = {{mechanical ventilation,temporary increased ventilation,EPBD,quasi-steady-state calculation method}},
  language     = {{eng}},
  location     = {{Cracow ; Lodz, Poland}},
  pages        = {{477--484}},
  publisher    = {{Technical University of Lodz}},
  title        = {{Quasi-steady-state calculation method of temporary increased ventilation during daytime}},
  year         = {{2010}},
}