Cost-effective and energy-efficient renovation measures of multi-family apartment buildings constructed during the million program - Where carbon dioxide emissions minimization is a key issue

Abstract

The Swedish construction and real estate sector has a significant impact on the total national carbon dioxide emissions and energy consumption. Thus, energy efficient and environmentally friendly renovation measures of existing buildings in Sweden plays an important role in the attempt to mitigate the climate changes. By applying the methodology developed by the IEA EBC Annex 56, this study focused on optimization of renovation measures to define energy, environmentally and cost-efficient renovation measures of multi-family apartment buildings located in southern Sweden. The analyzed reference building presented in this study is a high-energy consuming multi-family apartment building constructed during the mid 60’s in the city of Malmö. The present study includes an investigation of the current energy need of the building and compares it with different renovation alternatives with different intervention levels. The renovation measures studied within this project includes modifications to the building envelope, the ventilation system as well as an implementation of an individual metering and price charging system of the domestic hot water. The main aim of this project was to analyze different renovation alternatives in order to determine their effects on the energy consumption in the building, their financial profitability and their effects on the overall environmental impact of the building. Moreover, an additional analysis was conducted in order to study the potential co-benefits that may arise from the implementation of the renovation measures. The secondary aim of the project was to try to find renovation measures that would successfully reduce the annual energy consumption of the studied reference building down to a level where the current energy requirements established by the Swedish building sector was fulfilled.

The annual energy consumption of the studied reference building was assessed by the use of a dynamic energy simulation software. The effects of the linear thermal bridges were calculated separately under steady-state conditions. Moreover, the cost-efficiency of the studied renovation measures were evaluated by several conducted life cycle cost analyzes. In order to assess the environmental impacts related to the implementation of the studied renovation measures, a life cycle impact assessment, LCA, was conducted. The resulting co-benefits that arise from the implementation of the renovation measures were evaluated by using an assessment matrix provided by IEA EBC Annex 56.

The results of the study showed that it is possible to reduce the annual energy consumption of the building down to a level where the current energy requirements established by the Swedish building sector are fulfilled by implementing comprehensive renovation measures. The results of the life cycle cost analyzes indicates that the financial profitability of the renovation measures is mostly dependent of the balance between the initial investment costs, the saved energy costs that the measures entails and the assessed evaluation period. However, the life cycle cost analyzes conducted within this project shows that by combining the renovation measures with a number of legal aids, such as governmental subventions and increased monthly housing rent will radically affect the cost-effectiveness of the renovation measures in a positive way. The results of the life cycle assessments conducted within this project indicates that renovation measures that significantly reduces the dependence of district heating will also significantly reduce the annual CO2 emissions and primary energy consumption of the building over time. Although the results showed that the comprehensive renovation measures contributes to a rather high environmental impact in the upstream and core process, their implementation will still reduce the environmental impact of the building from a long-term perspective. Thus, the general conclusion is that the energy carrier and the quantity of the overall energy use in the building is the two biggest determining factors of how environmentally friendly the building will be from a long-term perspective.

The general conclusion of this research is that comprehensive renovation measures including modifications to the building envelope combined with ventilation and domestic hot water measures are preferable when retrofitting buildings with features similar to the studied reference building from a long-term financial and environmental perspective.

Popular Abstract

Sweden has set a national climate goal to reduce the specific energy use in buildings by 50% and becoming independent of fossil fuel energy until the year of 2050. The reasons why this climate goal was established was to avoid unnecessary energy costs in the Swedish society by becoming more independent to energy prices and to reduce environmental load in the Swedish society. A reduction of carbon dioxide emissions within the Swedish energy sector is inevitable in order to reach this goal. Energy efficiency is currently the cheapest and the most environmentally friendly solution to phase out fossil fuel energy and it creates opportunities to use power generated from wind turbines as well as solar energy. And the potential is huge. Sweden has currently the fifth highest energy use per capita in Europe; an unflattering top location for a country that likes to call itself a leading country in energy efficiency. The buildings and services sector currently accounts for nearly 40% of the total final energy use in Sweden, according to the Swedish Energy Agency. The greatest energy savings potential within the Swedish building sector lies in the buildings that were constructed during the ambitious public housing programme most commonly referred to as The Million Programme during the years from 1960 to 1975. The need for renovation of the multi-family apartment buildings constructed during the million programme are rather urgent. The buildings are worn down and sometimes on the verge of deterioration. Many of these buildings use twice as much energy compared to the multi-family apartment buildings that are being constructed today. However, the renovation work of these buildings poses a great challenge both economically and logistically but there is still a great potential for improving the energy efficiency of these buildings.

In this project, different types of potential energy-efficient renovation measures of a well-represented multi-family apartment building of the Million Programme located in the city of Malmö was studied and analyzed. The aim of the study was to find cost-effective renovation measures that also generates a carbon dioxide minimization to the building as well as improves the overall co-benefits of the building. Thus, an extensive literature study of different types of building materials and products was conducted in order to find the most cost-effective and environmentally friendly products. Another objective was to try to fulfill the current Swedish energy requirements for newly constructed and extensively renovated apartment buildings by applying energy-efficient renovation measures to the case study building.

The results of the study showed that it is possible to reduce the annual energy use of the case study building down to a level where the current Swedish energy requirements are fulfilled by implementing comprehensive renovation measures to the building envelope, the existing ventilation system and the domestic hot water of the building. The results also indicated that the financial profitability of the renovation measures is mostly dependent on the balance between the initial investment costs, the saved energy costs that the measures entails and the assessed evaluation period. However, by combining the renovation measures with a number of legal measures, such as governmental subventions and an increased monthly housing rent will radically affect the cost-effectiveness of the renovation measures in a positive way. The results of the study also indicated that renovation measures that significantly reduces the dependence of energy will also significantly reduce the carbon dioxide emissions of the building over time. The general conclusion of this research is that comprehensive energy-efficient renovation measures are preferable when retrofitting buildings with features similar to the case study building from a long-term financial and environmental perspective.

• author: Svensson, Christofer
• supervisor: Åke Blomsterberg
• organization: Division of Energy and Building Design
• course: AEBM01 20171
• year: 2017
• type: H2 - Master's Degree (Two Years)
• subject: Technology and Engineering
• keywords: Energy efficiency, Cost-effectiveness, Carbon dioxide minimization, Co-benefits, IEA EBC Annex 56, Renovation, The million program
• language: English
• id: 8918316
• date added to LUP: 2017-06-22 12:59:01
• date last changed: 2017-08-29 11:05:10