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Nearly-zero energy buildings are standard for new constructions in the European Union. The challenge for decarbonized cities is retrofitting the existing buildings. Retrofitting the existing buildings provides considerable opportunities for improving occupants' comfort and reducing global energy consumption and greenhouse gas emissions. Building retrofit is being considered one of the main approaches to achieve sustainability in the built environment at relatively low-cost and high-uptake rates. Although a broad range of retrofit technologies are readily available, methods to ascertain the most suitable set of retrofit actions for specific projects are still a practical challenge. This article first aims to develop and present a simulation-based multi-objective optimization model, named RETROSIM, to quantitatively assess technology choices in a building retrofit project. RETROSIM is a combination of a building energy simulation model and RETROSIM proprietary optimization engine. Secondly, in this study, RETROSIM is used to evaluate a building retrofit project as a case study to show the functionality of the proposed method. The study initiates with the single optimization of objective functions focusing on the building's characteristics and performance: primary energy consumption, global costs and thermal discomfort hours. Then this methodology is used to study the interaction between these conflicting objectives and evaluate their trade-offs. [ABSTRACT FROM AUTHOR]

The decarbonisation strategy of the building sector, which accounts for 24% of national greenhouse gas (GHG) emissions, is important to achieve climate neutrality in Korea by 2050. In this study, a bottom-up model and four scenarios were developed for examining scenarios for the decarbonisation of the residential building by 2050. A comparative analysis of energy consumption, GHG emissions, and investment cost was performed. The result showed that building energy performance improvement and heating fuel electrification are key measures for decarbonisation. We concluded that an investment of KRW 6.2 trillion per year would be required to achieve the 2050 decarbonisation scenario. Policy strategies were proposed for increasing investment in accelerating building retrofit, mandating zero-energy building (ZEB), and prohibiting gas boilers. [ABSTRACT FROM AUTHOR]

Built heritage plays an important role in making history visible in New Zealand's cities. However, ensuring that historic heritage can withstand future challenges such as climate change and seismic resilience is key to ensure its preservation, as the country has had countless examples of lost heritage due to earthquakes, fire, lack of maintenance and decay resulting from inadequate indoor environmental conditions. New regulations came into force in 2017 for earthquake-prone buildings, which set up timeframes for all buildings to achieve minimum structural standards. As a result, there are many seismic strengthening projects taking place, especially for Unreinforced Masonry (URM) buildings, identified as one of the most vulnerable construction types. However, the other future challenge for historic buildings will be to deal with climate change – ensuring buildings can withstand extreme conditions while maintaining comfortable indoor conditions, without demanding excessive energy input. So far, energy considerations have not been extensively included as parameters in retrofit projects, in existing policies or in practice. This contribution analyses current policies and practice for retrofitting historic buildings in New Zealand, aiming to understand the current barriers, challenges and possibilities for energy retrofitting historic buildings in the country as a combined strategy with seismic upgrading. [ABSTRACT FROM AUTHOR]

A novel approach for the identification of the optimal strategy for building retrofit is presented and applied to a case study in northern Italy. Increased envelope insulation, more efficient heat-generating systems, thermal distribution and terminal units, heating control systems, electric distribution systems, and renewable energies exploitation were considered as possible measures. A tailored multi-criteria decision analysis tool is developed to embrace the entire building life cycle and includes all the possible combinations in a discretized approach, with the aim of optimising conflicting design parameters, such as energy consumption, costs, GHG emissions, and comfort level. The proposed methodology is applied to two scenarios: nominal building parameters, and the validated model obtained using dynamic energy simulations. In both cases, most energy-efficient solutions are found to be optimal, however, large differences in overall energy consumption are found between the two scenarios resulting in different sizing of optimal renewable-energy installations and different electric distribution systems. A sensitivity analysis is also performed to estimate how results respond to the variation of input parameters. Despite a large difference between the two scenarios, the proposed methodology is found to be stable in identifying the optimal solution and offers full customisation features to adapt to different cases. [ABSTRACT FROM AUTHOR]

Arising from Ireland’s first measured nearly Zero Energy Building (nZEB) retrofit, this paper explores the potential impact of EU member state (MS) proposed cost-optimal nZEB retrofit implementation on Irish building codes, and in turn how that may impact current best practice in low-energy retrofit design practices. The paper compares cost-optimal methodologies to best practice and discusses how design retrofit strategies could change in the context of market drivers and value engineering. The implications for capital investment and return are discussed, highlighting variations from EU guidance, with specific regard to net present value (NPV), scenario analysis, building lifespan, residual value and calculation period in the Irish cost-optimal calculations. A case study of a 1974 non-residential building highlights nZEB retrofit best practice immediately prior to MS cost-optimal calculations, demonstrating the importance of fabric-first interventions in extending building lifespan and reducing energy demand. The reported demonstrator project is the first measured site nZEB retrofit in an Irish context, outperforming reported cost-optimal energy consumption, costing less than new-build and adding an additional 40-year building lifespan. The paper concludes that the proposed Irish cost-optimal nZEB retrofit packages may drive design strategies towards active solutions, and away from fabric-driven retrofits, whilst not complying with EU guidance. [ABSTRACT FROM AUTHOR]