Application of an energy sensitivity analysis when refurbishing buildings in Sweden

Abstract

The European commission have set targets regarding the reduction of emission of greenhouse gases, the improvement of the energy efficiency and the use of renewable resources of energy respectively by 20 % by the year of 2020. Swedish targets are even more ambitious compared to the European Commission that aims to reduce the greenhouse gas emissions by 40 %, improve the energy efficiency by 20 % and make 50 % of the energy be produced from renewable resources. The building sector is one of the major responsible for energy consumption, therefore renovating the existing non-efficient building have a big role to achieve this target. During the 1960’s, the Swedish government initiated a program to build a million dwellings to supply the demand of the rapidly growing population. Today, the majority of these buildings need renovation.
The aim is to perform and present a method for assessing the sensitivity of different refurbishing measures in an actual building case in terms of total energy use that could then be applied to equivalent buildings. The goal is to distinguish the most influencing refurbishing parameters and performing a life cycle cost to determine whether they are reasonable to implement or not.
This study is based on a real building located in Lund at Linero. The building is nearly 50 years old and was built by Lunds Kommuns Fastighets AB, LKF during the Million programme project. LKF and Cityfied provided the required data to validate a simulated model built in the software IDA ICE. The sensitivity analysis was performed by using a screening-based method where extreme values for refurbishing parameters were studied in order to determine their importance i.e. sensitivity index, from an energy aspect. Three renovation packages were created to assess the energy use, percentage of people dissatisfied and cost efficiency.
By using this method, the most influencing parameters on the energy use could be identified. Renovation package #1 was able to reduce the energy use by 45 % but was not the most cost beneficial. Renovation package #3 which included parameters that had a lower influence on the energy use, showed to be the most cost efficient out of the three packages.
The SI method does not include all the important factors that should be considered when performing a renovation. The energy demand is highly impacted by the dependency of the set ranges. The wider it is, the higher the SI becomes and the narrower it is, the lower it gets. As the cost is not included in the method, it sets no boundaries whether how wide the range can be. This will mislead the investor to make decisions based on inadequate information and is therefore not recommended.

Popular Abstract

Climate change is nowadays one of the main concerns in the European Union. To try to reduce the impact caused by human activities, the European Commission set some directives and targets regarding the energy production and consumption, and the reduction of emission of greenhouse gases. The building industry is one of the biggest responsible for energy consumption and C02 emission. And the renovation of the stock of old buildings represent a great opportunity to achieve those targets.
The study aimed to explore a method that could help designers in the first stage of a refurbishing project, where the guidelines of the project are defined. The method assesses the impact of different refurbishing measures in a real building, and the goal is to find and list the renovation parameters from the one that have more energy-savings potential to the least during the use of the building. After, the cost during the period of 50 years is calculated in order to determine if it is reasonable to implement those parameters or not.
The studied building is located in Lund, and this building was part of the Million Programme Project, initiated by the Swedish government during the 1960’s, to supply the demand of new dwellings for the growing population. The building was first simulated (using the software IDA ICE) as at it is, and the simulation results were validated by the data provided by LKF and Cityfied. LKF and Cityfied are currently doing renovation in the area, and have some data about the energy consumption of the buildings. After validating the base case (the building how it is now), all the chosen parameters (e.g windows type, insulation thickness, lighting, etc.) were simulated separately, changing just one parameter at the time and keeping the other parameters as it is in the base case. Two different values were tested for each parameter, for example a very good window and a cheap window, comparing the results gotten from the two different values with the base case, it was possible to get the percentage of the potential of energy saving for each parameter and rank it. The parameters that achieved a minimum of 10 % of energy savings potential was grouped into what it was called Renovation Package #1, and the parameters below the benchmark of 10 % was grouped into the Renovation Package #3.
The costs of refurbishing and the energy consumption during the period of 50 years was assessed for each individual parameter and also the renovation packages. But the total cost is just calculated after the results and it is not considerate when ranking the parameters. Renovation package #1 was able to reduce the energy by 45 % but it was not the most cost beneficial. Renovation package #3 which included the parameters that had a lower influence on the energy use, showed to be the most cost efficient.
This method does not include all the important factors that should be considered when doing a renovation, for example the cost. The influence of the parameter is highly impacted by the range of values studied. The wider it is, the higher the influence becomes and the narrower it is, the lower it gets. As the cost is not included in the method, it sets no limits whether how wide the range can be. This will mislead the investor to make decisions based on not accurate information and is therefore not recommended.

• author: Tsuge Costa, Gabriela Miti and Hermansson, Denise
• supervisor: Åke Blomsterberg; Niko Gentile
• organization: Division of Energy and Building Design; Department of Architecture and Built Environment
• course: AEBM01 20181
• year: 2019
• type: H2 - Master's Degree (Two Years)
• subject: Technology and Engineering
• keywords: Sensitivity analysis, Energy performance, Million program project, Refurbishment, IDA ICE
• language: English
• id: 8974396
• date added to LUP: 2019-04-12 13:38:33
• date last changed: 2019-04-12 13:38:33