Effect of the heating systems on heating loads in residential buildings considering the design parameters

Increasing population and high rates of internal migration leads to higher residental building demand. When the final energy consumption ratio has identified according to different sectors in Turkey, industry seems to be at the first place with 37% from the total pie chart. Moreover, building sector catches it up with the ratio of 35% which does not seem to be less important than industry. Their consumed energy amounts are both seems close enough. When these ratios are considered in detail, another truth has come as the consumption amounts are keep growing in every single year eventhough their ratio from the pie seems to be the same. The one third of this final consumption rate refers to use of the energy for the purpose of providing thermal comfort by required heating and cooling systems. According to the data obtained from Ministry of Energy and Natural Resources in 2008 data, natural gas founded as the most important and usable fuel type with usage rate of 26%. Buildings with the longest lifecycle period within all sectors and by being nearly the number one for it's final energy consumption rate, any king of energy efficiency activity could lead for efficiency rates up to 30% to 50% easily. Residential heating systems do not only cause huge energy consumption rates, but also increase emission rates of greenhouse gas by using natural gas as their main fuel resource and release carbondioxide gas to the atmosphere. There are 4 main types of heating systems which are used in Turkey as; • direct heating systems, • indirect heating - central heating systems, • district heating systems and • solar heating systems. Direct heating systems such as heating stoves and fireplaces were used mostly in the past years when there is no central heating system application. With the emerging technology, especially in the big cities of the country, central heating systems were started to be used. Radiator heating systems and the underfloor heating systems became the most commonly used systems within residential buildings. As the third type, district heating systems are also commonly used in both big and some small cities in the country. They are more suitable for buildings and building groups such as school campuses and hospitals. District heating systems have long return and supply pipes different than central systems only with a boiler unit and an internal heating distributer pipes for residence. Solar heating systems are more commonly used in the southern parts of the country. For solar heating systems, solar collector units such as solar thermal collector panels and photovoltaic panels can be easily used especially on the roof tops of the residential buildings. While considering different heating system types and their energy consumption rates, design parameters of the building should also be taken into account. Design parameters can be divided into 2 main categories as external environmental parameters and building design parameters. Within the external environmental parameters; climate, natural lighting and topographic conditions should be examined well before the evaluations. For the building design parameters; building placement, building form, building orientation and building envelope characteristics should be evaluated together with the building heating systems in order to achieve energy efficiency. In scope of this dissertation study, most commonly used heating systems which are radiator heating systems and underfloor heating systems in Istanbul/Turkey has identified. Their classifications according to their usage frequency and fuel demand (which is natural gas most commonly) have examined. Design parameters of the residential building in terms of building form, building envelope characteristics, building window wall ratio as well as climatic and regional data of the project site has searched out. In order to specify the optimum application of all the design parameters, a case study held with the case building model. Case building model has 100 m2 floor area and 3 m floor height. In Designbuilder simulation program, 3 different buildings with the same area and volume were designed in 3 different forms. For each geometry, both radiator heating systems and underfloor heating systems are designed according to Turkish standards and simulated within the program. Not only the building geometry has criticized in terms of heating loads, but also facade construction materials are evaluated by 2 different construction materials. Moreover, window-to-wall ratio from 30% to 70% is applied for southern façade in order to see how window-to-wall ratio effects the heating load of the residential building. When evaluating the window-to-wall ratio on the southern façade, three different types of glasses have criticised as well. They have chosen as double glazed argon filled glass, low E coated double glazed argon filled glass and triple glazed argon filled glass. As a result, optimum combination of; • Shape factors: 2:1, 1:1, 1:2 • Building envelope materials: Gas Conctrete and Stone • Window glass types: double glazed argon filled glass, lowE coated double glazed argon filled glass and triple glazed argon filled glass • Window wall ratio: 30%, 40%, 50%, 60% and 70% • Building heating systems: radiator heating systems and underfloor heating systems have evaluated in terms of building heating loads and carbondioxide emissions. In the scenarios, the building simulated with gas concrete material on the exterior wall requires less heating load compared to the building with stone material as a exterior wall. By using gas concrete an decrease of 19,52% in heating load can be achieved annually. Different window glass properties affect the building heating loads significantly. The lowest heating load was achieved by triple glazed argon filled glass. According to the calculations done, the saving can reach up to 23,02% when window glass type is changed with triple glazed argon filled glass. Increasing the value of window-to-wall ratio at the southern facade directly decreases the heating load of the building. While increasing this ratio from 30% to 70% heating load of a building can decrease by 35,05% which refers to 1304 kWh annually. While changing the building from 1:2 to 1:1, the heating load of a building can decrease up to 16,36%. From 1:1 to 2:1, this load increases by 20,05%. Moreover, if the building form is changed from 1:2 to 2:1, heating load can be reduced by 32,53% which is equal to 1078,61 kWh. During the simulations of various scenarios, it has been found out that the maximum decrase rate of 23,51% can be achieved while only by switching the radiator heating system with the underfloor heating system without changing any other parameter. As a result of 180 different simulation outputs, the building with radiator heating system, 30% window-to-wall ratio at the southern facade, double glazed argon filled glass window, stone material at the envelope and 1:2 form is found out to be the building with highest heating load by 4594,42 kWh and 1449,17 kg CO2 emission. Against the building above, the building with underfloor heating system, 70% window wall-to-ratio at the southern facade, triple glazed argon filled glass window, gas concrete material at the envelope and 2:1 form is found out to be the building with the lowest heating load by 2016,44 kWh and 1061,42 kg CO2 emission. According to the results gathered by building simulation program outputs within this dissertation, it has understood that only by changing heating system, window-to-wall ratio, window glass type, form and the construction materials with more efficient alternatives, heating load of a building can be decreased up to 56,11% which is equal to 2577,98 kWh. Based on the calculation results, with a decrease of 56,11% in heating load, 387,58 kg of CO2 emmission can also be eliminated annualy. As a result, heating loads and CO2 emissions can be reduced by basing on the heating systems and improving design parameters. In this study two heating systems have been analyzed, however more alternatives are still possible. In order to reach general results and provide optimum alternatives ensuring minimal energy load, different alternatives need to be improved and analyzed and cost factor should be taken into consideration.