## 1 Introduction  
The rising attention to energy consumption problems is raising the interest for the applications of thermal remote sensing in urban environments. In the report of the Intergovernmental Panel on Climate Change, it is clearly stated that the most cost-efficient way to decrease CO\({}_{2}\) emissions is through the implementation of energy-efficient retrofitting measures in the building sector [1]. Furthermore, in a recent letter to the President of the United States, a consortium of several industrial partners requested that his administration adopt policies to provide householders with reliable and actionable information at a large scale about the energy use of their buildings [2]. It is obvious that efficient building diagnostic tools can make a major contribution to fulfilling these goals. Thermography, including all of the techniques for the analysis of the infrared radiation emitted or reflected by objects in the thermal infrared region of the electromagnetic spectrum, provides the opportunity to analyze both the thermal characteristics of the materials lying on the ground and many processes related to the exchange of heat between the surfaces; its importance has been demonstrated in a wide range of military, civil, industrial and scientific applications [3,4]. This science can be successfully used also for energy saving purposes in the urban environment (with particular emphasis on housing stocks and industrial areas) involving several types of stakeholders beside householders, such as public agencies and municipalities, urban planners, entrepreneurs in the field of the energy performance of buildings, constructors and real estate agencies. Thermal remotely-sensed imagery can be widely used in urban landscapes, because it provides a synoptic and time-synchronized grid of temperature data, even of very large areas, and therefore, it permits analysis at different scales of urban building materials, energy use and losses, surface energy budgets and urban heat island effects [3,5,6]. In particular, aerial thermographic surveys in urban areas can reach a very high level of spatial detail, covering, at the same time, very large areas if compared to traditional survey techniques [7,8], thus resulting in being very attractive for the evaluation of the energetic performance of buildings at an urban scale. These kinds of applications continue to increase, especially in continental areas or in cold climates, like the UK, Canada and northern United States [2,9]. The results of these studies are usually raster maps of surface temperatures, which can be easily implemented and processed in the Geographic Information System (GIS) for the creation of spatial decision support systems (SDSS) intended for decision makers. Although, when compared with the past, advances in thermal infrared detectors and techniques have facilitated obtaining high-resolution thermal images over large areas, for a correct quantitative evaluation of land surface temperatures (LST) and the implementation of the derived maps in the GIS environment, several processing phases are required. In addition, an appropriate choice of the instruments to be used and a detailed planning and execution of the surveys are required. In fact, it is necessary to correct the acquired images, taking into account the effects of the acquisition geometry, the topography of the scene, the influence on the measured values of the atmosphere and of the physical-chemical properties of the different materials lying on the ground. Moreover, several additionaldata, besides the high-resolution thermal imagery, are required to perform all of these steps of processing and to compute accurate surface temperatures; among them, multispectral imagery, digital elevation models, atmospheric measurements, ground surveys and GNSS recordings. From the obtained temperature data of building surface elements, estimations about the energetic quality of the building shell can be assessed.