Conference article

Exergy Analysis of Different Solutions for Humidity Control in Heritage Buildings

M. Molinari
KTH, Stockholm, Sweden

T. Broström
Gotland University, Gotland, Sweden

Download articlehttp://dx.doi.org/10.3384/ecp110572041

Published in: World Renewable Energy Congress - Sweden; 8-13 May; 2011; Linköping; Sweden

Linköping Electronic Conference Proceedings 57:39, p. 2041-2048

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Published: 2011-11-03

ISBN: 978-91-7393-070-3

ISSN: 1650-3686 (print), 1650-3740 (online)

Abstract

Energy use in the building stock represents a major contribution to the total energy use in developed countries. Increasing limitations to the energy demand of the new buildings have been imposed by the building codes in the last decades; which resulted in improved building envelopes.

Yet; in many cases it is not either technically or economically feasible to improve the existing building shells. A typical example is represented by historical buildings; such churches and old buildings; which often may not be improved for aesthetical or economic reasons. Often poorly insulated; such buildings would require a high energy demand to keep them at the preferable hygro-thermal conditions. As a consequence they are often left unheated; which also affects the usability of these buildings. However; the risk of moisture damage often requires them to be slightly heated to a certain temperature.

As the energy demand is linked to the possibility of improving the building shell; for instance by adding insulation or making it more airtight; the exergy approach gives interesting insights on the problem. Exergy analysis emphasizes the thermodynamic valuable part of the energy demand in the building and straightforwardly defines the minimum energy demand for a certain process. The energy demand being equal; it is still possible to lower the exergy demand and consumption. A lower exergy demand paves the way to the exploitation of renewable sources; such as solar power.

Often the main task is to keep the RH humidity within a certain range. Aim of this paper is to perform a theoretical exergy analysis of three different solutions for lowering the RH in the building. The basic approach keeps the temperature of the indoor space at a constant level. A second approach-the so-called conservation heating- consists in letting the temperature vary according to the maximum allowed indoor relative humidity. In the third case the target is reached by means of a dehumidification process. Advantages and disadvantages of the different approaches are shown under the energy and exergy points of view.

The present research is done within the framework of the “Spara och bevara” project; which targets cost-efficient solutions for the conservation and the use of heritage buildings in Sweden and the IEA Annex49 and ESF COSTexergy projects; which aim at energy-efficient buildings and communities through the application of the low-exergy approach.

Keywords

Exergy analysis; Energy efficient buildings; Heritage buildings; Renewable energy

References

[1] Commission of the European Communities; Action Plan for Energy Efficiency: Realising the Potential; 2006.

[2] International Energy Agency ECBCS Annex 37; Heating and Cooling with Focus on Increased Energy Efficiency and Improved Comfort - Guidebook to IEA ECBCS Annex 37 Low Exergy Systems for Heating and Cooling of Buildings. VTT; Technical Research Centre of Finland; 2003.

[3] International Energy Agency. Low Exergy Systems for High Performance Buildings and Communities. [Online] 2005-2009; http://www.annex49.com.

[4] International Energy Agency ECBCS Annex 39; Vacuum insulation panels; study on VIP components and panel for service life prediction of VIP building applications; 2005.

[5] European Commission; Directorate General for Energy & Transport; The new Directive on the energy performance of buildings – Moving closer to Kyoto; 2003.

[6] P. Sakulpipatsin Exergy Efficient Building Design; Doctoral Thesis; Department of Building Technology; University of Delft; 2008.

[7] M. Shukuya; A. Hammache; Introduction to the concept of exergy - For a better understanding of low-temperature heating and high-temperature cooling systems; VTT Research Notes; 2002.

[8] T. Broström; G. Leijonhufvud; Heat pumps for conservation heating. Proceedings of the 8th Symposium on Building Physics in the Nordic Countries. 2008; pp. 1143-1150.

[9] M. Alhazmy; Minimum work requirement for water production in humidification-dehumidification desalination cycle; Desalination; 2007; pp 102-111. doi: 10.1016/j.desal.2007.03.002.

[10] P. Sakulpipatsin et al.; An Exergy Application for Analysis of Buildings and HVAC systems. Energy and Buildings; 42; 2009; pp 90-99. doi: 10.1016/j.enbuild.2009.07.015.

[11] D. Camuffo; (editor). Church Heating and the Preservation of the Cultural Heritage. Guide to the Analysis of the Pros and Cons of Various Heating Systems. Electa; 2006.

[12] A. Bejan; Advanced Engineering Thermodynamics. John Wiley; New York; 1997.

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