University of Twente Student Theses


Future sustainable terraced houses in Cardiff

Ernst, Karin (2014) Future sustainable terraced houses in Cardiff.

Abstract:There are many studies done about energy usage and comfort in residential buildings and it is often concluded that the comfort will decrease due to the climate change. The climate change will lead to amongst others a global warming of the atmosphere, melting of ice caps and rising of sea level. In the UK the increase of temperature and precipitation are the greatest changes. For Cardiff a higher outside temperature and solar radiation are essential changes, because they might increase the interior temperature in buildings and therefore decrease the comfort. The effect of the climate change on the comfort and energy use of buildings will vary by region and by the type of houses. Heavyweighted houses are not strongly influenced, because they have a greater heat capacity. So the inside temperature does not vary as quick as the outside temperature and the changes of inside temperature over day and in the night will be less. For the municipality in Cardiff it is interesting how the comfort and energy use in houses of Cardiff will change and what methods will help to reduce the energy use whilst maintaining today's comfort. This aim leads to the following research question: How should the design of houses in Cardiff be due to the changed climate in 2030, 2050 and 2080? The found methods help to avoid the adaptation of ad-hoc mechanical installations which increase the emission of greenhouse gases and therefore this study is giving a first print of how the future climate will affect the comfort and energy use of commonly built houses in Cardiff and which sustainable methods are more effcient than others. First of all, literature studies will give the description of future weather and help to create a building standard that represents the recently built terraced houses in Cardiff. The weather in Cardiff will change to a warmer outside temperature and a stronger solar radiation. Next to these two developments, the wind speed, precipitation and other natural factors are expected to change, but in this research the focus lies only on outside temperature and solar radiation. The temperature is increasing continuously from 16°C to 21°C in summer, but the solar radiation appears to increase inconsistently (from 1187 kJ/m2 to 1274 kJ/m2). It is expected that the higher temperature and solar radiation will heat up the building and therefore the comfort will decrease. But this effect on buildings in Cardiff will be discussed later by doing the simulation. The building standard is a terraced house with two bedrooms, kitchen, living room, entrance hall, bathroom, toilet and an attic, where a working couple is living. So the couple is leaving in the morning at 7pm for work and they will return at 6pm. The evenings and at the weekends the couple will stay at home most of the time. A gas central heating is installed so that a defined inside temperature can be maintained. But the gas central heating does not only regulate the temperature to maintain comfort, natural ventilation should also help by cooling down the inside temperature. After collecting all these data a model can be created. Using the simulation program EnergyPlus the comfort in terms of uncomfortable hours is examined as well as the energy use in terms of heating, cooling and total energy usage. Therefore the weather data in .epw format, created by the project PROMETHEUS, and a standard building model is uploaded. Based on the simulation of the standard building model it appears that the future energy use will be reduced in summer about 75% and in winter about 28%. This means that the total energy use will decrease from 68 793MJ to 4374MJ in summer season until the end of the century. This result is contrary compared to studies made earlier, but this difference can occur due to different methods used, locations, climate and models. Nevertheless, eight different changes in design and construction are examined: improvement of the insulation, change of the wall window ratio (WWR) and adaptation of shading devices. The insulation is improved, by adding two insulation layers to the exterior wall so that a double cavity wall is created. Concerning the roof, the insulation layer is extended and the windows are changed from double glazed to triple glazed ones. The WWR is changed in two ways. Firstly, it is increased from 0.12 to 0.19 and secondly, it is reduced to 0.06. For the third solution overhangs are adapted above each window. In a last model a balcony on the first floor is installed additionally to the overhangs. From the analysis it appears that the lower WWR is the most effcient one compared to the others, because it reduces the energy use about five times more than the majority of solutions. This is why less solar radiation is entering the rooms. Windows are the exterior surfaces with the highest heat conductivity and if the window surface is decreased, the surface with a better insulation is increased. Therefore the building will loose less heat. The second most effcient solution is to increase the WWR. This is not as effcient as reducing it, because a greater WWR will let more solar radiation enter the building, but on the other hand it also leads to a greater ventilation. Redevelopping the whole external surface, so that it reaches the building regulation of 2013, is effcient, but not as much as changing the WWR. But retrofitting the entire exterior surface is the most effcient concerning redevelopping. This is logic, because in case wherein only the windows is retrofitted, the house would still loose heat by the wall and the roof. Thus it can be seen that the building regulations reduces energy usage and therefore it is good to update the regulation regularly. Adapting shading devices is not recommended solution because the comfort decreases slightly and the energy use is increasing. But these results and recommendation are especially for Cardiff and it would be different if the research is done for another city or another building type.
Item Type:Essay (Bachelor)
Faculty:ET: Engineering Technology
Subject:56 civil engineering
Programme:Civil Engineering BSc (56952)
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