Developing Residential Building Typologies with Thermal Efficiency Approach for Residential Buildings in Babolsar City

Regarding the substantial increase of energy consumption in the building sector, it is necessary to consider construction characteristics in the policymaking processes in order to improve the building energy efficiency. Basically, it is infeasible to improve the energy efficiency of the building industry based on the energy characteristics of individual buildings. Political strategies are developed based on the study of building typologies following the climatic conditions of each region. There are limited studies on the types of residential buildings, most of which emphasize on architectural concepts and building formation. Lack of research in the field of housing typology in Iran highlights the necessity to develop an approach toward energy-efficient residential buildings. This study aims to recognize the typologies of residential buildings, focusing on the parameters affecting energy consumption, in Babolsar City, which is selected as a city representative of the humid and mild climate in North of Iran. This paper also tries to evaluate and improve the thermal performances of the recognized typologies based on the Iranian National Building Code (Part 19: Energy Efficiency). The methodology is completed into four main sections: 1) Reviewing the literature in order to identify and select the criteria for developing residential building typologies 2) Conducting a survey on a number of residential samples based on the statistics and distribution of residential buildings in Babolsar city 3) Classifying buildings and presenting plan typologies based on statistical and pictorial analyses 4) Investigating the heat transfer coefficient of the recognized typologies and introducing the optimal patterns according to the Iranian National Building Code (Part 19: Energy Efficiency). Using a descriptive-analytical strategy, this research is based on statistical methods of quantitative analysis and simplifies residential building plan concepts. The data are collected on the field by investigating 384 residential buildings constructed in a period between 1963 and 2016 in Babolsr City. Each sample is scrutinized by completing a questionnaire. The questionnaires are created in two parts: 1- the building general information including, the architectural type (apartment or villa), the age of the building, the number of families, the neighborhood type, the building gross area, the number of bedrooms and building type (flat/apartment, attached/ semi-attached); and 2. the construction details including, the physical parameters of the building such as materials, windows/glazing type,  overhang size, thermal insulation, indoor space height, area of external surfaces / controlled / uncontrolled spaces, heating and cooling system, and building envelope details. In other words, all required information and parameters affecting the building energy consumption are included. The residential building samples are classified into ten categories based on the number of families, building type, and neighborhood unit. Typologies are divided into two groups of “villa” and “apartment” housing. Each group has four subsets numbered as A, B, C, and D which differs in terms of total plan area and the position of conditioned/ unconditioned zones. In order to determine a typical plan for each category, all possible plan concepts for each group were designed and codified. Then, the plans of all 384 samples were simplified and codified and categorized in their relevant groups. Finally, a group of higher frequency was chosen as the group representing the typical plan.  The eight recognized typologies of this research can be used as reference in any research on housing for evaluating and predicting thermal performance, cost, and energy analysis. The analysis of the thermal performance of the building typologies demonstrated that none of the typologies comply with the Iranian National Building Code (Part 19), in terms of conformity with heat transfer coefficient. Adding a 5-cm thermal insulation, with a heat transfer coefficient of λ = 0.041, to the external wall, and also replacing windows with double-glazed ones are necessary to improve their energy efficiency and achieve the minimum requirement of the building code. The results of this study can be used as a basis for further investigations on energy-efficient building design, in order to improve the thermal performance of buildings rather than developing a regional energy efficiency building code for building construction in the mild climate in north of Iran. The presented typologies can be used as a reference for energy auditing, retrofit actions, and refurbishment measurements, and for quantifying the energy-saving potentials of existing buildings. They can be applied to the existing buildings stock to increase energy performance by considering the optimal tradeoff between policymaking and cost. The results are also important for developing and modifying regulations. Further studies are required to make the result of this study applicable to other climatic regions in Iran.