Jonathan Cullen
University of Cambri
Jonathan Cullen is the Lecturer in Energy, Transport and Urban Infrastructure, at Cambridge University Engineering Department (CUED) and a Fellow at Fitzwilliam College, Cambridge. He leads the newly formed Resource Efficiency Collective, exploring options to reduce energy use and emissions through resource efficient solutions. Jonathan holds an undergraduate degree from the University of Canterbury, and MPhil and PhD degrees from the University of Cambridge, all in engineering. He is the co-author of Sustainable Materials: with both eyes open, described by New Scientist as “clear, well-supported, and vital” and recently listed in Bill Gate’s top six reads for 2015.
The provision of two energy services, passenger transport and space heating in buildings, drives almost a third of global energy use. Delivering these energy services more efficiently has the potential to reduce absolute... [ view full abstract ]
The provision of two energy services, passenger transport and space heating in buildings, drives almost a third of global energy use. Delivering these energy services more efficiently has the potential to reduce absolute energy use and associated GHG emissions. However, to achieve this requires a systemic understanding of the entire energy value chain, including knowledge of the efficiency potentials at each stage in the value chain and how specific policies can be targeted promote efficient energy use.
Previous research from our group argued that a distinction between conversion devices and passive systems is needed to determine efficiency limits for the delivery energy services (Cullen and Allwood 2010a, 2010b; Cullen et al. 2011). This is because the engineering approaches for improving conversion devices (e.g. improved combustion and heat transfer, reduced mechanical friction) differ fundamentally from those required for passive systems (e.g. streamlined aerodynamics, increased insulation, air tightness). Thus, delivering mobility and thermal comfort more efficiently requires a multi-faceted approach made up of tailored technical strategies targeted to each stage of the energy value chain.
In this research, we argue that policies aimed at improving energy efficiency should also be specifically targeted and bespoke. We choose two UK case studies, automobile transport and space heating in buildings, and examine historical efficiency improvements to understand the effects of efficiency policies over time. We find that for space heating, recent polices have targeted both heating systems (conversion devices) and building insulation/air-tightness (passive system) leading to improvements in both areas. However, in contrast, efficiency policies for passenger transport are more broad and target fuel efficiency (e.g. L/100km), allowing manufacturers to neglect potential gains from improving aero-dynamics and rolling resistance (passive system).
References:
Cullen JM, Allwood JM (2010a) The efficient use of energy: tracing the global flow of energy from fuel to service. Energy Policy, 38(1)75–81
Cullen JM, Allwood JM (2010b) Theoretical efficiency limits for energy conversion devices. Energy, 35(5)2059–2069
Cullen JM, Allwood JM, Borgstein EH (2011) Reducing energy demand: what are the practical limits? Environmental Science and Technology, 45(4)1711–1718
• Sustainable energy systems , • Decision support methods and tools
