Energy and Buildings 50 (2012) 324–330 Contents lists available at SciVerse ScienceDirect Energy and Buildings j our na l ho me p age: www.elsevier.com/locate/enbuild A simulation appraisal of a switch of district to electric heating due to increased heat efficiency in an office building Milorad Boji ´ c ∗ , Slobodan Djordjevi ´ c, Jovan Malesevi ´ c, Marko Mileti ´ c, Dragan Cvetkovi ´ c Faculty of Engineering, University of Kragujevac, Sestre Janjic 6, 34000 Kragujevac, Serbia a r t i c l e i n f o Article history: Received 18 February 2012 Accepted 2 April 2012 Keywords: District heating Electric heating Office building Inter unit heat flow Tariffs EnergyPlus a b s t r a c t This research addresses the existing phenomenon in Eastern Europe related to office buildings heated by district heating. For enhanced heating efficiency, an office building is thermally insulated and/or run at a decreased space temperature. After that, in an office inside the building, the tenants may switch from district to less costly electricity heating due to the customary tariffs for district and electrical heating. The effects of this switch are analyzed by using software EnergyPlus. For the investigated office, it is found that a characteristic value of its heat consumption exists below which the heating switch decreases heating costs. In addition, the value of the heat consumption is recognized below which the heating switch also yields the decreased fossil fuel consumption and CO 2 emission. For all cases, the consumed heat consumption, the consumed fossil energy, CO 2 emission, and economic effects are recorded for heating devices in the excluded office. Furthermore, it is analyzed how these variables are influenced by heat transfer between the investigated office, and the adjacent offices. © 2012 Elsevier B.V. All rights reserved. 1. Introduction Scientific evidences of climate change and effects of greenhouse gases emissions have become obvious. Energy use in all types of buildings represents a huge portion, about 40%, of the total EU energy consumption. In Eastern Europe to enhance heat efficiency and decrease heat consumption in office buildings heated by dis- trict heating (DH), their adequate refurbishment and use turn out to be a priority. Although these measures should yield environ- mental benefits for society through a reduction in the fossil energy consumption, and thus, the CO 2 emissions, it is noticed that after decrease in heat consumption by refurbishment and low-heat use, the office owners would exclude their offices from DH. In the excluded offices (EOs), they will replace DH with electrical heat- ing (EH). Namely, EH proves to be cheaper than DH. Then, this may diminish energy and environmental effects of refurbishment and yield to higher use of fossil fuels and larger emissions of CO 2 to environment. The motive for this investigation is the situation with the pub- lic DH in the city of Kragujevac that there are many requests to exclude offices from the DH and heat them by electricity as the electrical heating is cheaper. The cheaper electricity heating in the Abbreviations: DH, district heating; EH, electrical heating; EO, excluded office; IUHF, inter unit heat flow. ∗ Corresponding author. Tel.: +381 64 8449694; fax: +381 34 330196. E-mail address: bojic@kg.ac.rs (M. Boji ´ c). EO may exist because of several reasons that can act separately or together: (1) reduced heat consumption due to better thermal insulation of the building, (2) reduced heat consumption due to the lower temperature in the EO, (3) existing tariffs for heating by different heating systems, and (4) the existence of the inter-unit (office) heat flows (IUHFs). These phenomena may yield to addi- tional fossil energy consumption and additional CO 2 emissions in atmosphere. When there are no regulatory and legal acts, this space is very easy to switch to another system of heating. This situation may establish additional energy policy in some country that will ban the exclusion of these offices from DH or ask for the fulfilment of some additional conditions to approve the exclusion. Lower heating price by electricity due to in-force district heating tariffs was noted by Bahnmueller et al. [1]. Namely, they found that there are quite a lot of cases, where tenants which switched to using electricity, pay much less than their neighbors still supplied by district heating. Gustafsson [2] concluded that DH prices must be competitive with the prices of EH when retrofit measures are used on existing buildings. The most significant issue of prices for consumed heat relates to the influence of heat prices on an amount of the decrease in the fossil fuel consumption and CO 2 emissions by energy efficiency actions. Due to different heat tariffs, the heat costs differ, and in most cases the reduction in heat consumption lowers the heat costs for tenants. However this dependence may be either stronger as in the case of electricity or poorer as in the case of DH. At the other hand, it is noticed that the reduction in the heat consump- tion sometimes may yield to increase in the fossil fuel consumption 0378-7788/$ – see front matter © 2012 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.enbuild.2012.04.004