The eco-refurbishment of a 19th century terraced house (energy, carbon and cost performance for current and future UK climates)

Much of the existing UK housing stock has a poor standard of energy performance and the residential sector currently accounts for around 25% of the country’s carbon dioxide (CO2) emissions. The eco-refurbishment of dwellings is a key action if the UK is to meet national targets for reducing carbon emissions, mitigating global warming and alleviating fuel poverty. Older properties tend to be the hardest to heat and the most difficult to refurbish, and this is particularly true for the UK’s five to six million terraced homes, many of which not only date back to the 19th century, but they represent early examples of mass urban living, hence they have strong cultural and architectural resonances. It is a significant challenge to the building industry, therefore, to sustainably renovate these buildings whilst maintaining their aesthetic character. This research analysed large amounts of monitoring data provided by the government’s ‘Retrofit for the Future’ programme for a 19th century, solid wall end-terraced house in Liverpool, England, in order to determine how the key features of the retrofit design would contribute to the improved energy performances of the refurbished houses. The aim of this renovation was to go beyond current UK thermal building regulations and to achieve the more exacting German Passivhaus standard. Analysing two years of extensive monitoring data revealed that the retrofitted house used 60% less energy and produced 76% fewer CO2 emissions than the estimated figures for a pre-refurbished house. Solar thermal panels provided over 61% of the hot water required in two year of occupancy. During the first year of occupancy the highest indoor air temperature was 26.5°C and indoor CO2 levels exceeded 1000PPM for 340 hours, or 11% of the occupied time. Using probabilistic UK future weather data and the dynamic thermal modelling software, DesignBuilder, the thermal performance of the house was simulated under different climate change probabilities with results indicating that the need to minimise over-heating, together with maintaining acceptable internal temperatures, will become increasingly important factors in retrofit design decision making. Finally, long term energy cost savings and carbon payback times for this case study were evaluated. The results of these calculations showed that the most favourable energy bill savings occurred when gas prices were rising – this gave a payback time of less than forty-three years. A carbon payback time of less than eight years means that there was no need for climate change sensitivity analysis of the model and the measures in the carbon payback time study. In addition, the Cost per Tonne of Carbon Saved (CTS) calculation showed that fabric measures, especially external wall insulation, are the most cost and carbon effective measures in the eco-retrofitted Liverpool terraced house

Analysing the benefits and challenges of retrofitting rural dwellings in Hunan, China to the Passivhaus EnerPHit standard

Abstract Chinese rural housing largely consists of uninsulated reinforced-concrete apartment blocks with poor energy performance. These dwellings are structurally sound, costly to demolish and challenging to recycle. Retrofit is, therefore, potentially more worthwhile than new build. Currently, there is no Chinese standard for retrofitting dwellings. This research examined the viability of applying the German EnerPHit retrofit standard to Chinese rural dwellings in Hunan, southern China (hot summers and cold winters). Dwellings were evaluated in terms of building structure, materials and systems, and a common type of apartment was selected. The real-world thermal performance of the dwelling was monitored and then the dwelling was modelled using the dynamic thermal simulation software DesignBuilder and Passivhaus Planning Package (PHPP). Monitoring data were used to validate the software’s predicted values. Next, energy-efficient EnerPHit retrofitting measures were incrementally applied to the dwelling model. Simulation results indicated that it was possible for the apartment to meet the EnerPHit standard if an optimised combination of thermal measures were applied. Good ventilation heat recovery was essential for winter comfort and minimum energy consumption; in summer, using adjustable shading and a high efficiency humidity recovery ventilation system was important. Appropriate natural ventilation schedules contributed in lowering cooling energy demand.</jats:p

Sensitivity analysis of the impact of environmental product declaration values on whole life carbon assessment: A case study using expanded polystyrene insulation for the retrofit of a building in Turkiye

Until recently, reducing the energy required to service a building (the operational energy) was the main aim of controlling carbon emissions from the built environment. It is now recognised that the energy required to make a building (the embodied energy) also has a crucial role in creating a net zero carbon future. The methodologies for quantifying embodied carbon are less developed than those for operational carbon, and more research is required to refine the embodied carbon metrics used when a building’s whole-life carbon emissions are calculated in a Life Cycle Assessment (LCA). One such metric is the Environmental Product Declaration (EPD), a document which can be used in different countries to quantify a product's environmental performance. EPDs are crucial data for conducting an LCA study of a building. However, despite recent efforts to standardise them, there are still inconsistencies between EPDs produced by different countries or manufacturers, even for materials with similar thermal and physical properties. This study considered some of the reasons for variations in EPDs for one product type, expanded polystyrene insulation (EPS). Factors such as (i) the LCA databases and software generators used for the EPDs, (ii) material mixes and manufacturing methods, (iii) country energy production mixes, and (iv) transportation distance from material source to the factory were considered in the analysis. As a case study, this paper examined the effects of selecting different EPDs for expanded polystyrene insulation on the final LCA results from the retrofit of a mid-rise residential building in Turkiye. Differences in EPDs demonstrated a fourfold difference between the highest and lowest upfront carbon impact results of building retrofit. This size of discrepancy indicates the need to choose the most appropriate EPD for a building/location when performing an LCA. Practical Applications Selecting an EPD when conducting an LCA for a new building or retrofit is generally left to the assessor’s judgment and knowledge, which varies greatly depending on the assessor’s background, especially in the construction sector. This study suggests an informed decision-making method over an example of EPS insulation material when the EPD options were none or limited to building locations like Turkiye. </jats:sec