Transient buoyancy-driven flows in multi-storey buildings: the fluid mechanics of linked vessels

The research focuses on the development of mathematical models for describing transient flows within and between connected fluid-filled vessels. The fluid mechanics of connected vessels is of broad interest and numerous examples may be found in industry, the built environment and the laboratory. This work focuses primarily on the interaction between three connecting vessels and considers two main areas of application: (i) the so-called `double-tank' method, as used by experimental fluid dynamicists to stratify environments, and (ii) the passive transient ventilation of multi-storey buildings. An analytical description of the double-tank method, a classic example of liquid exchanges under controlled (constant) flow rates between horizontally connected vessels, was developed. Subsequently, a new technique was proposed, modelled and tested which enabled a broader range of density stratifications to be set up and without the use of pumps. This technique enabled liquids to drain freely under gravity from one vessel to another - the rates of liquid transfer no longer constant but functions of the instantaneous liquid depths. Modelling the fluid mechanics of multi-storey building ventilation added additional tiers of complexity as air and heat exchanged between rooms drive turbulent mixing and there is complex feedback between the individual rooms. Three vessels were again considered, two storeys connected to a common atrium, and the development of the buoyancy- driven flow following the activation of heat sources was investigated. A description of the transient response of the ventilation in an atrium building leading to a steady state, as typically achieved during the course of a day, was developed. Wind pressure variations and solar heat gains in the atrium were also incorporated. The effect of atria geometry on the ventilation of adjoining rooms was established and shown to be analogous to either an `assisting' or an `opposing' wind. When `opposing', the ventilation flow rate reduced. For a strongly `opposing' atrium, a reversal in the direction of flow through the storey occurred, revealing the possibility of multiple flow regimes during the transients - the dynamics of which were explored. Finally, the building ventilation model was generalised to n storeys (n > 2) connecting to a common atrium. Controversially, the implications of the predictions indicate that current atrium designs do not guarantee enhanced flow as is generally accepted

Assessing progress towards the EU energy efficiency targets using index decomposition analysis

To track the real progress towards the energy efficiency targets, this report examines the drivers behind EU energy consumption trends using index decomposition analysis. Energy consumption trends are driven by several factors beyond energy efficiency improvements, including economic activity, demography, lifestyle changes, weather and other factors. These can all have a profound effect in the aggregate energy use, irrespective of the impact of energy efficiency policies and measures. The separation of energy efficiency impacts from structural and activity changes of the economy as a whole is conducted by applying the widely-used Logarithmic Mean Divisia Index (LMDI) methodology to study the aggregated and sectoral energy consumption changes at EU and MS levels.JRC.C.2-Energy Efficiency and Renewable

Energy efficiency upgrades in multi-owner residential buildings: Review of governance and legal issues in 7 EU Member States

This report reviews the legal, management and administrative obstacles in multi-owner buildings in 7 selected Member States and identifies good practices that help overcome identified issues across these Member States. The information is collected through a questionnaire distributed to legal and energy efficiency experts at national level with the aim to deepen our understanding on the legal implications of the current apartment ownership and management structure in each country and identify energy efficiency policies that encourage investments in this field. A workshop was also organised in November 2017 in Brussels with the aim to discuss these issues in more detail and draw policy recommendations on how to revise existing condominium and rental acts to make them more conducive to energy efficiency upgrades and investments in apartment buildings.JRC.C.2-Energy Efficiency and Renewable

Analysis of the annual reports 2017 under the Energy Efficiency Directive: Summary Report

This report discusses the progress towards the 2020 Energy Efficiency targets and towards the implementation of the provisions of the Energy Efficiency Directive 2012/27/EU (EED), providing an overview of the main energy trends in the European Union with special focus on the period 2005-2015. It is based on the last EUROSTAT data available and on the analysis provided by Member States within their Annual Reports 2017, under the EED.JRC.C.2-Energy Efficiency and Renewable

Energy Service Companies in the EU: Status review and recommendations for further market development with a focus on Energy Performance Contracting

Building on its previous reports, investigating the status of the ESCO market in the EU, the Joint Research Centre (JRC) reviewed the efforts made by Member States to stimulate the market of energy services, and in particular the market for EPC, during the period 2014-2016 and the current size of the ESCO market. The findings in this report show new developments since the last report published by the JRC in 2014 for the period 2010-2013.JRC.C.2-Energy Efficiency and Renewable

Practices and opportunities for Energy Performance Contracting in the public sector in EU Member States

The public sector is one of the key users of energy in Europe. Although, the relative energy consumption of the public sector is rather small, i.e. “only” about 5-10% of the total energy demand of European Member States, with an annual energy bill €47 billion (Borg & Co. et al. 2003), there are several reasons to focus on improving the energy performance of public buildings and public installations.JRC.C.2-Energy Efficiency and Renewable

Analysis of the annual reports 2019 under the Energy Efficiency Directive

This report discusses the progress towards the 2020 Energy Efficiency targets and the implementation of the provisions of the Energy Efficiency Directive 2012/27/EU (EED), providing an overview of the main energy trends in the European Union with special focus on the period 2005-2017. It is based on the latest available EUROSTAT data and on the information provided by Member States in their Annual Reports 2019 submitted under the EED. Our analysis has shown that 2015 was a turning point for the progress towards the energy efficiency targets due to a reversal in the preceding 5-year declining consumption trend of 2010-2014. Energy consumption increased mildly in 2015 and continued to rise in 2016 and 2017; the latest increase in 2017 point to a gap of 3.4% and 5.3% with respect to the EU final and primary energy consumption targets of 2020, respectively. At end-use level, rising energy consumption in transport and industry were the main causes of this progress slowdown. The assessment of the 2019 Annual Reports generally confirmed good progress with regards to implementation of various provisions the Energy Efficiency Directive including those stipulated in Article 7 on energy efficiency obligations. While a few Member States reported new measures which can be viewed positively in light of the need to narrow the gap towards the targets, more intensified policy efforts are needed. Beyond the various information gaps identified by this report, our analysis suggests that achieving central government requirements on energy efficiency may be challenging and accelerated efforts across all sectors are crucial in ensuring that sufficient progress is made in the coming years.JRC.C.2-Energy Efficiency and Renewable

Assessing the progress towards the EU energy efficiency targets using index decomposition analysis in 2005-2016

Energy consumption trends are driven by several factors beyond energy efficiency, including economic activity, demography, lifestyle changes and weather. These can all have a profound effect in the aggregate energy use, irrespective of the impact of energy efficiency policies and measures. As more and more countries are relying on their energy efficiency targets as a means to address unprecedented challenges resulting from increased dependence on energy imports, scarce energy resources and climate change, robust methodologies that enable monitoring and measuring progress towards these targets are increasingly important. To identify the driving factors and their contributions behind the latest energy consumption trends in the EU, the Logarithmic-Mean Divisia Index method (LMDI) method, a widely-used IDA method, was applied to study both aggregated and sectoral energy consumption changes at EU and MS levels over the period 2005–2016 in this report.JRC.C.2-Energy Efficiency and Renewable

Accelerating energy renovation investments in buildings

At today's renovation rate of around 1% of buildings per year, a timely transition of the EU building sector towards climate-neutral levels by 2050 cannot be ensured. To accelerate energy efficiency investments in this area, the European Commission has intensified its efforts in recent years, with specific calls to strengthen the existing financial framework, increase funding levels, diversify types of financial models and explore new supporting mechanisms. Various private and public financial and fiscal mechanisms for energy renovations in buildings are currently available in Europe in the form of non-repayable rewards, debt financing, equity financing, etc. This report provides a country-by-country overview of the most important public schemes identified across the EU, and investigates new private financial products in place to stimulate more energy efficiency investments in residential, commercial and public buildings. Good practices are identified based on the criteria of impact, cost effectiveness, ambition level of energy efficiency upgrade, funding sustainability/continuity, scalability and outreach to hard-to-reach groups.JRC.C.2-Energy Efficiency and Renewable

Review of 50 years of EU energy efficiency policies for buildings

The reduction of energy demand in buildings through the adoption of energy efficiency policy is a key pillar of the European Union (EU) climate and energy strategy. Energy efficiency first emerged in the EU energy policy agenda in the 1970s and was progressively transformed with shifting global and EU energy and climate policies and priorities. The paper offers a review of EU energy policies spanning over the last half century with a focus on policy instruments to encourage measures on energy efficiency in new and existing buildings. Starting from early policies set by the EU in response to the Oil Embargo in the 1973, the paper discusses the impact of EU policies in stimulating energy efficiency improvements in the building sector ranging from the SAVE Directive to the recently 2018 updated Energy Performance of Buildings Directive and Energy Efficiency Directive. The review explores the progress made over the last 50 years in addressing energy efficiency in buildings and highlights successes as well as remaining challenges. It discusses the impact of political priorities in reshaping how energy efficiency is addressed by EU policymakers, leading to a holistic approach to buildings, and provides insights and suggestions on how to further exploit the EU potential to save energy from buildings