A study on energy and cost efficient retrofitting of historic buildings: a case study on the building of Izmir Tekel Basmudurlugu

After the oil crisis that broke out in the 1970s, the energy issue became a global problem. As a result of the usage of fossil fuels, released gases cause the greenhouse effect by accumulating in the atmosphere, resulting in environmental problems, especially global warming and climate change. Rapid population growth and the increase in energy demand cause the decrease of energy resources. Therefore, usage of alternative energy sources and reducing energy usage become a necessity. It is known that building sector is highly responsible for the energy consumption and greenhouse gasses emission. European buildings are responsible for 40% of energy consumption and 36% of CO2 emissions according to the document published by European Union. It is clear that building sector has a significant energy saving potential. One of the most important regulations for the improvement of energy efficiency is ''Directive on Energy Performance of Buildings'' published by the European Union in 2002. According to this directive for each member, it is necessary to develop national methods for the calculation of the energy performance of the buildings and to certify all the buildings by this method and to ensure minimum energy performance requirements defined by the legislation in new and existing buildings. In 2010 EU published recast version of Energy Performance of Buildings Directive of EU (EPBD-Recast) to indicate that energy retrofit action must be cost-optimal. In this context Turkey, as a candidate country for EU, made legal regulation as 'Energy Efficiency Law-2008' and 'Energy Performance Regulation in Buildings'. To calculate the energy performance of the buildings, a national calculation method(Bep-Tr) was developed. Today, a large percentage of building stock has been built in periods when energy efficiency is not on the agenda. For this reason, besides designing new buildings with high energy performance, it is also important to improve the energy performances of existing buildings. For increasing the energy performance of existing buildings' energy retrofit measures can be taken such as thermal insulation application, replacement of window etc. Historical buildings that have an important percentage in existing buildings, energy retrofit actions should be handled differently than contemporary ones. For increasing energy performance of the building, retrofit measurements can be applied to the building. While determining retrofit measures for the historical building, buildings historical and cultural value must be taken into consideration. In this study, it is aimed that increasing energy performance of the historical building by cost-optimal retrofit solutions. İzmir Tekel Headquarter building which is taken as a case study at this study was built in the 1930's. Therefore, while increasing energy performance of this building is one of the primary purposes, preservation of the historical value of the building is one of them. In this study, a method consisting of 6-steps starting from the determination of the reference building was followed. In this method; Step 1: The reference building has been identified. Information on the thermophysical, physical, active and passive systems of the reference building has been obtained. Step 2: The building model was created in the Energy Plus database DesignBuilder. While the building model is being built, features such as climate, location, direction, and function of the area where the building is built are modeled. Step 3: Energy retrofit measures have been identified. Step 4: The energy performances of the improvements in the DesignBuilder simulation program have been obtained. Step 5: The global cost of the retrofit measures are calculated using the net present value method. Step 6: Determine energy and financial efficiency improvement measures for the building After obtaining information about reference building, building model was created in DesignBuilder simulation program. Then, energy performance of case study was calculated. In this study based on energy consumption and economic performance, the measures enabling energy are examined with the aim of improving the energy performance of historic buildings. Therefore, passive, active and passive&active retrofit measures were determined with the concern of historic value of the building. Passive measures are internal wall insulation, replacement of window with high performance and attic floor insulation. Active measures are the replacement of HVAC system. Passive&active retrofit measures consist of the combination of active and passive retrofit measures. All building elements(wall, window, and roof) u- values were calculated in İzoder-TS825 program and introduced to the dynamic simulation program. Then Designbuilder simulation program used for assessing energy retrofit measures. The energy performance of the building is taken into account only regarding heating and cooling consumption. At first, energy performance of passive retrofit measures were assessed including, inner insulation, replacement of the window, attic floor insulation as single, double and triple retrofit packages. Inner wall insulation alternatives were determined as composite glass wool plate(3cm/5cm), composite rock wool(3cm/5cm) plate and rock wool(3cm/5cm). Window retrofit alternatives were determined as; double-glazing window and low-e coated double glazing window. The energy performance of active and active&passive retrofit measures, including replacement of the heating-cooling system, were assessed. In this part, retrofit measures which have the best performance regarding energy performance were determined. Then, the cost-effectiveness of the energy retrofit measures was assessed by the net present value method, which is the method given in the Energy Performance Directive at Buildings-Recast. For cost analysis, first the initial investment cost of retrofit measures was determined. To determine initial investment costs of measures, 'Unit Price List' was used published by Environment and Urban Ministry of Turkish Republic. Then, energy consumption costs of retrofit measures were determined according to their energy consumption for 20-year lifespan of the building. In this study, the interest rate is 13% natural gas unit price is 0,08165564 (TL/kWh)and the electricity unit price is taken as 0,219735 (TL/kWh). The cost-effective retrofit measure determined by using net present value method. Assuming that building has no income, the net present value of retrofit measures which is closest to the zero is the most effective one regarding finance. To determine cost-optimal energy retrofit measure, net present value and energy consumption relation were analyzed. Also, the relationship of initial investment cost- energy consumption cost were analyzed. The net present value vs. primary energy consumption graph is drawn by using Minitab program. The lowest point of the graph which is indicating the cost-optimal measures are determined. In this study, two cost-optimal energy retrofit measures were determined. One of them isd1-p3-ç3 alternative, which is included replacement of window with high performance, application of attic floor insulation and application of VRF system for HVAC. The other retrofit measure is d10-p1-ç1 which is included only wall insulation and application of VRF system for HVAC. In this cases, energy savings are achieved by 55% and 63%, respectively. As a result, the efficiency of retrofit measures differs while considering only energy performance, only cost and also both of them. - Considering only energy efficiency: the case in which the VRF system and bd2-p2-ç3 measure application (wall insulation, window replacement, and attic floor insulation). - Considering only cost efficiency: Only the VRF system application where actively improved. - Considering both energy and cost efficiency: The situation where the d1-p3-ç3 or d10-p1-ç1 measures of the VRF system in which both passive and active systems are improved can be applied. This study shows how energy and cost parameters can change optimal retrofit measure while improving the performance of historical buildings. Considering energy and cost parameters together while improving the performance of historic building does not only prevent the depletion of energy resources but also contributes to the economy of the country. Therefore, energy and cost parameters should be handled together to determine optimal solution while improving the energy performance of the building.