Many cities in the world are putting in place their own robust carbon reduction strategies in response to, or in advance of, leadership from central government. As the powerhouses of economic growth, cities use vast amounts of energy and consume resources from hinterlands that stretch across international borders. However, the population density of cities can also provide opportunities for significant efficiencies in terms of the provision of building services and the mobility of people and goods. In this programme of work, we propose to centre our activities on two cities: Xi'an, China and Portsmouth, UK which are notable both for their cultural heritage and for their population density (Portsmouth has the highest population density of any city in the UK). Both cities have published ambitious plans for reducing city-wide carbon emissions but also have large stocks of ageing buildings and infrastructure. This programme of work will: (a) develop an overall understanding of current buildings, mobility and energy services in both cities; (b) identify low disruption and scaled-up retrofit methodologies taking into account the particular characteristics of the two cities; (c) carry out modelling of city-wide retrofit and systems integration, at both the neighbourhood and district scales including building refurbishment, district energy and micro generation geared to improve buildings for their users. In all our modelling and building performance evaluation, we will take into account anticipated climate change projections and the adaptation required to maintain or exceed current levels of thermal comfort. (d) Address adaptive urban logistics to meet mobility needs within the two cities while pursuing carbon reduction targets through a series of targeted workshops with practitioners in the field from both countries. (e) Through a combination of modelling and monitoring, we will identify smart solutions harnessed to inform users and reduce consumption. Crucially, the modelling will be validated by real energy consumption datasets, gathered from both secondary sources (provided by our partners and from others) and primary, from a combination of sensor deployments and surveys. The latter will take the form of monitoring of a sample of multi occupancy buildings for a range of relevant parameters including temperature, power consumption, humidity and carbon dioxide. The building performance data provided by the sensor deployment will be supported by user survey data exploring perceptions of thermal comfort, overall wellbeing (satisfaction with life, health, employment and so on) and attitudes to energy saving and the cost of energy. This will link the purely techno-economic assessment of energy saving interventions to their potential social impacts. The outcomes of this programme will take the form of validated tools and guidance distilled from the project results in order to support city planners in their decision making processes concerning building asset refurbishments and the likely impact on wellbeing resulting from such improvements. A central aspect of the programme will be to foster collaboration and knowledge transfer between both researchers and practitioners in China and the UK. There are areas, for example district heating, of which there is far more experience of in China than the UK, very relevant to densely populated UK cities like Portsmouth. In other areas such as energy efficiency standards for new buildings and building energy assessment techniques, there is potential for knowledge transfer from the UK to China. In the final year of the project a joint UK-China workshop will be held to bring together researchers and practitioners in the fields of planning, energy, building services and local government, in order to disseminate the results of the programme, to test out and receive feedback on the support tools and to foster further collaboration.

Potential Impact:
The UK has a specified carbon dioxide reduction target of 80% by 2050 from 1990 levels. In relation to this, the UK has one of the oldest and most inefficient building stocks in the world which accounts for around 40% of its carbon emissions. The present financial constraints and lack of appetite for increased taxation mean that the public sector in particular will be forced to live with its current building stock for the foreseeable future. With rising fuel costs and risks of summer overheating driven by climate change projections of prolonged heat wave events, this building stock is facing a stark challenge. We need to reduce both winter space heating loads and avoid a 'one hot summer switch' to costly, inefficient split air-conditioning systems as the climate continues to warm. This project looks to address these challenges in a manner which is rapidly deployable with realistic economic terms that the public sector could buy into.

In light of the on-going economic growth of China, energy efficiency needs to be dramatically improved if carbon emissions from the built environment are to be held constant, let alone reduced. In Xi'an - one of the most ancient cities in the world - a large number of historical buildings have been maintained in order to protect cultural heritage, but these buildings are currently occupied mainly by those on the lowest incomes. This project will seek low disruption solutions to improve the energy performance of such buildings and hence the health and comfort of the inhabitants, while maintaining the cultural value of the built assets.

In the UK context, the city of Portsmouth, with its ageing housing stock, has areas of the city with the proportion of households in fuel poverty at around 25%, where many of the householders live in social housing and have complex needs affecting their wellbeing. Energy savings in the public sector follow through as a benefit to the wider public through reductions in council and general taxation. The working life of non-public sector buildings which are of low rentable value due to energy performance may be extended through low cost façade analysis approaches such as proposed here. In a wider context, between 1998 and 2008 the UK became a net importer of gas and oil. Reducing heat demand in our non-building stock, is seen as a key pathway to reduce our nationally critical security of supply exposure, along with radical changes in transportation.

The rapidly expanding market for goods and services in China has been targeted by the UK government as a key growth area for UK business. In recent years, companies from the EU have signed agreements with several rapidly growing cities in China to provide modern district energy services, including Chongqing, Tianjin and recently Beijing. Other cities like Xi'an have an existing established heat network, but the city is growing fast to encompass new areas that were previously agricultural land and addition some parts of existing networks run on steam, now considered old fashioned from efficiency and safety points of view. There is therefore also a potential market in retrofit of mature district energy systems in China and this programme will both highlight this potential and bring together district energy practitioners from the UK and China.

While not on the same scale as in China, and lagging well behind many European neighbours, district energy and combined heat and power are expanding in the UK due to twin advantages of avoided electricity import costs and lower carbon energy supply. The work carried out in this programme will strengthen the case for the expansion of modern district energy networks by quantifying their benefits on a city wide basis - which in turn could help to create jobs in the low carbon economy. The same will be true of energy efficiency services more generally, which in the UK government estimates to account for about 136000 jobs and had sales of £17.6 billion in 2010/11.