A multi-layer approach for estimating the Energy Use Intensity on an urban scale

Various governments are planning their cities to be climate responsive by reducing the energy consumption and carbon emissions according to different scenarios whilst maintaining good indoor comfort conditions. A robust and reliable tool that can estimate the Energy Use Intensity (EUI) of a city is required. This paper presents a new bottom-up engineering-based multi-layer approach able to analyse the energy performance of existing settlements of every size by retaining as much information as possible about their complexities. The process involves i) creating a 3D model of the urban area, ii) building up templates representing different building characteristics such as functions, the age-band of the buildings and operating schedules, iii) running dynamic thermal simulations and iv) displaying the EUI or total energy demand in the 3D model which can be post-processed for further analysis. This approach offers a flexible simulation process according to various purposes, which is particularly useful in decision-making for urban energy retrofitting or planning for new areas. The hourly high-resolution outcomes would benefit the detailed analysis of energy efficiency strategies in order to achieve carbon reduction. The application of this approach is demonstrated for the case of Yuzhong district in Chongqing municipality, China

Eco city development in China: addressing the policy implementation challenge

Over the last few decades, China has seen a steep rise in diverse eco city and low carbon city policies. Recently, attention has begun to focus on the perceived shortcomings in the practical delivery of related initiatives, with several publications suggesting a gap between ambitious policy goals and the emerging realities of the newly built environment. To probe this further, in this article we examine – based on the policy network approach – how the gap between high-level national policies and local practice implementation can be explained in the current Chinese context. We develop a four-pronged typology of eco city projects based on differential involvement of key (policy) actor groups, followed by a mapping of what are salient policy network relations among these actors in each type. Our analysis suggests that, within the overall framework of national policy, a core axis in the network relations is that between local government and land developers. In some cases, central government agencies– often with buy-in from international architecture, engineering and consulting firms – seek to influence local government planning through various incentives aimed at rendering sustainability a serious consideration. However, this is mostly done in a top-down manner, which overemphasizes a rational, technocratic planning mode while underemphasizing interrelationships among actors. This makes the emergence of a substantial implementation gap in eco city practice an almost predictable outcome. Consequently, we argue that special attention be paid in particular to the close interdependency between the interests of local government actors and those of land and real estate developers. Factoring in this aspect of the policy network is essential if eco city implementation is to gain proper traction on the ground

Green housing transition in the Chinese housing market : a behavioural analysis of real estate enterprises

The concept of green housing has been introduced in China to deal with climate issues in the housing sector. Green housing development requires a complex socio-technical transition based not just on green materials or technologies, but also, and most importantly, on the behavioural transition of housing market actors. Little is known about how Chinese real estate enterprises are responding to the green housing transition within a Chinese context. Addressing this gap, our research aims to determine whether, and to what, extent Chinese real estate enterprises are transitioning toward greener housing practices and what constraints may exist. This research gap is particularly pressing given the Chinese government’s ambitions to promote energy efficiency in the new urban building sector by requiring 50% of urban new buildings to be green buildings by 2020 (NDRC, 2016). Our research reveals Chinese real estate enterprises face a dilemma of ‘going green’ and a range of institutional constraints that currently frustrate their uptake of green housing practices. Our research furthers knowledge on environmental and housing market governance within non-western and non-liberal contexts

Natural ventilation potential for residential buildings in a densely built-up and highly polluted environment. A case study

The application of Natural Ventilation (NV) as a measure to improve comfort conditions in transition and summer periods has been a topic of research on the spotlight for years. However, there is a lack of knowledge about how the combined effect of a dense urban layout with high pollutant concentrations may affect its potential. This paper addresses this gap by running detailed thermal simulations for a typical apartment flat located in the Yuzhong district of Chongqing city (China) using a holistic approach that makes use of: i) wind pressure coefficients on building facades from urban-scale CFD simulations, ii) hourly measured values of PM2.5 concentrations and weather variables and iii) indoor environment measurements for validation purposes. Scenario analysis revealed the average amount of air change rates achievable in a year varies from 8 to 15 ACH according to the windows orientation. These figures drop down to around 2 ACH when taking into account reduced windows opening time when outdoor PM2.5 concentrations are too high. The resulting natural ventilation potential of the case study decreases from 4234 h when outdoor pollution is neglected to 2707 and 529 h when considering the exposure thresholds set by the Chinese government and the WHO respectively