Denia Kolokotsa

Local climate change and urban heat island mitigation techniques – the state of the art

AbstractIncrease of the ambient air temperature in cities caused by the urban heat island phenomenon has a seri- ous impact on the economic and social system of cities. to counterbalance the consequences of the increased urban temperatures important research has been carried out resulting in the development of efficient mitigation technologies. the present paper aims to present the state of the art in terms of local climate change and urban heat island mitigation techniques. In particular, developments in the field on highly reflective materials, cool and green roofs, cool pavements, urban green and of other mitigation technologies are presented in detail, while examples of implemented projects are given.

Energy utilizability concept as a retrofitting solution selection criterion for buildings

AbstractRetrofitting is widely explored as one of the energy conserving opportunities for existing buildings, in which both passive and active solutions are carefully evaluated. However, when different retrofitting solutions are combined and applied to a building, the total energy savings potential, which is less than the sum of the savings from applying the various individual retrofitting solutions, is considerably reduced and the synergies among the various technologies need to be understood and evaluated. In this study, the concept of utilizability is employed for the analysis of multiple energy retrofitting solutions in buildings and is defined as the ratio of energy savings derived from applying combined solutions to a building over the sum of individual energy savings from applying individual solutions. It is aimed at providing a better understanding of the combined retrofitting solutions. The sensitivity analysis on the utilizability value further provides a selection criterion for retrofitting sol...

Adaptive lighting controllers using smart sensors

The aim of this paper is to present an advanced controller for artificial lights evaluated in several rooms in two European Hospitals located in Chania, Greece and Ancona, Italy. Fuzzy techniques have been used for the architecture of the controller. The energy efficiency of the controllers has been calculated by running the controller coupled with validated models of the RADIANCE back-wards ray tracing software. The input of the controller is the difference between the current illuminance value and the desired one, while the output is the change of the light level that should be applied in the artificial lights. Simulation results indicate significant energy saving potentials. Energy saving potential is calculated from the comparison of the current use of the artificial lights by the users and the proposed one. All simulation work has been conducted using Matlab and RADIANCE environment.

Cities for Smart Environmental and Energy Futures: Urban Heat Island Mitigation Techniques for Sustainable Cities

The most apparent impact of urban development on the environment is the rearrangement of its biophysical attributes. By altering the nature of the surface and generating large amounts of heat, urbanized areas modify the microclimate and air quality. The urban heat island phenomenon, which serves as a trap for atmospheric pollutants, deteriorates the quality of life and has a socio-economic impact in the urbanised areas, has been a research subject at least for the last 100 years.

Energy poverty in Europe: Challenges for energy efficiency

Energy and fuel poverty is an increasing problem in the European Union. Although the specific conditions vary from country to country the drivers defining fuel and energy poverty are similar in all Europe. This paper aims to present the characteristics of the low income housing including details on the thermal and environmental quality of houses and the specific energy consumption. Existing energy efficiency and passive solar technologies to improve the energy and environmental quality of low income houses are reviewed and discussed while real projects addressing issues related to the energy performance of poor households are presented.

Passive Cooling of Buildings: Present and Future Needs: Recent Progress on Passive Cooling Convective Technologies

The maximisation of energy efficiency in buildings can be performed by successful demonstration of the passive technologies. Passive cooling is passing to a phase of maturity, while significant research has been performed worldwide. The aim of this chapter is to underline and review the recent state-of-the-art technologies for passive cooling convective strategies for buildings and their contribution in the improvement of the indoor environmental quality as well as in the reduction of cooling needs. The paper starts with a short introduction in passive cooling needs and continues with the analysis of the two passive cooling convective techniques, i.e. ground cooling and night ventilation.

Technical advances in the EU-Cool Roof project

Cool materials keep the roof cool under the sun by reflecting the solar radiation away from the building and radiating the stored heat away during night time. The potential of the technology is very promising at EU level and, in particular, in the Mediterranean area. EU supports the Cool Roofs Project, where important technical actions are developed. The technical and scientific activities include: development of the first EU cool materials database; implementation of five case studies with different building typologies equipped with different cool materials; development and validation of a dedicated toolkit; production of the cool materials handbook. The paper summarises the most significant results achieved in the project.