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Estimating exergy prices for energy carriers in heating systems: Country analyses of exergy substitution with capital expenditures
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2011 (English)In: Energy and Buildings, ISSN 0378-7788, Vol. 43, no 12, 3609-3617 p.Article in journal (Refereed) Published
Abstract [en]

Exergy represents the ability of an energy carrier to perform work and can be seen as a core indicator for measuring its quality. In this article we postulate that energy prices reflect the exergy content of the underlying energy carrier and that capital expenditures can substitute for exergy to some degree. We draw our line of argumentation from cost and technology data for heating systems of four European countries: Austria, Finland, The Netherlands, and Sweden. Firstly, this paper shows that the overall consumer costs for different heating options, widely installed in those countries, are in the same range. In this analysis we derived an overall standard deviation of about 8%. Secondly, additional analysis demonstrates that the share of capital costs on total heating cost increases with lower exergy input. Based on the data used in this analysis, we conclude that for the case of modern cost effective heating systems the substitution rate between exergy and capital is in the vicinity of 2/3. This means that by reducing the average specific exergy input of the applied energy carriers by one unit, the share of capital costs on the total costs increases by 2/3 of a unit.

Place, publisher, year, edition, pages
2011. Vol. 43, no 12, 3609-3617 p.
Keyword [en]
Exergy, Energy prices, Buildings, Heating
National Category
Building Technologies
URN: urn:nbn:se:kth:diva-65554DOI: 10.1016/j.enbuild.2011.09.034ISI: 000298268600037ScopusID: 2-s2.0-80755137040OAI: diva2:492820
QC 20120227Available from: 2012-02-08 Created: 2012-01-25 Last updated: 2012-11-21Bibliographically approved
In thesis
1. Exergy and Parametric Analysis: Methods and Concepts for a Sustainable Built Environment
Open this publication in new window or tab >>Exergy and Parametric Analysis: Methods and Concepts for a Sustainable Built Environment
2012 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Energy use in the world is continuously increasing. In the last 30 years the use of primary energy worldwide has more than doubled and it is mainly supplied with fossil fuels. A more efficient use of energy in the built environment has to be pursued if a more sustainable development is to be attained.

The housing sector accounts for a major share of the energy use. Both in residential and commercial buildings, energy is mainly used for heating. Heat is energy with low quality. Traditional energy analysis methods, by failing to consider the energy quality, cannot give a holistic insight of the potential for reducing the energy used in the built environment. Exergy, instead, provides a tool to quantify the energy quality based on thermodynamic grounds.

In this thesis a methodology based on both the reduction of the energy demand and exergy demand in buildings is proposed to mitigate the problems related to the energy use in buildings through a reduced and more efficient use of energy.

The complex relations between building parameters to reduce the energy demand are managed with parametric analysis tools. The potential for energy demand reduction is investigated by means of screening analyses, local sensitivity analyses and global methods. A method for assessing the potential reduction of the energy demand in existing buildings and to evaluate the cost-efficiency of renovation measures based on the screening analysis is introduced and tested on two building typologies. In parallel, a program tool for parametric energy simulations, Consolis Parametric, has been developed on the core of an existing dynamic software, Consolis Energy +.

Factorial analysis has been used to investigate the relations between the reduction of the energy demand and of the energy supply when ground source heat pumps are used for heating and cooling. Optimal configurations- dependent on the insulation of the building- of number of boreholes and spacing were identified for minimum electricity consumption.

In the second part of this thesis exergy is used as tool for the definition of the efficient energy use in the built environment. The analysis of a multi-step heat pump to supply energy at two temperature levels, for space heating and domestic hot water production, exemplified how the reduction of the exergy loss can lead to a more efficient use of energy. The analysis was performed by means of SEPE, a modular software program developed in this work for exergy analysis in buildings.

For the systematic reduction of the exergy losses in the built environment, an important prerequisite is the reduction of the exergy required by the building. Systems like floor heating and cooling, based on low difference emission temperature, are examples of low-exergy systems. Buildings with reduced need of exergy input increase the efficiency of systems like heat pumps and enhance the use of low quality energy, like waste heat and energy from low temperature renewable sources.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2012. x, 69 p.
Meddelande. Institutionen för byggvetenskap, ISSN 1651-5536 ; 209
National Category
Civil Engineering
urn:nbn:se:kth:diva-105380 (URN)978-91-7501-539-2 (ISBN)
Public defence
2012-12-12, B2, Brinellvägen 23, KTH, Stockholm, 13:00 (English)

QC 20121121

Available from: 2012-11-21 Created: 2012-11-20 Last updated: 2013-02-15Bibliographically approved

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