Low exergy systems for heating and cooling of buildings

Abstract

ABSTRACT: The low exergy approach should be the key concept in any long term strategy aiming at creating a sustainable built environment. In recent years, how to build sustainable houses has been a constant source of discussion. A highly efficient usage of energy and all of the potentials in the involved energy flows are undisputable mandatory for that. To find and to quantify further potentials in energy use, the thermodynamic concept of exergy can be beneficial. Energy, which is entirely convertible into other types of energy, is exergy (high valued energy such as electricity and mechanical workload). Energy, which has a very limited convertibility potential, such as heat close to room air temperature, is low valued energy. Low exergy heating and cooling systems use low valued energy, which could also easily be delivered by sustainable energy sources (e.g. by using heat pumps, solar collectors or others). Common energy carriers like fossil fuels deliver high valued energy. Heat emission systems, that are often part of the building construction itself, have a much longer service lifetime than building service equipment, such as boilers or chillers. With appropriate emission systems, the overall system design of a building is flexible in meeting future requirements, and they are open to being supplied by low temperature energy sources, such as renewable ones. There are already a number of different low temperature components, systems and technologies on the market, such as the known hydronic floor heating systems. Examples of buildings equipped with low exergy heating and cooling systems from all over the world and from all kinds of buildings, from newly erected to retrofit, from dwellings to commercial buildings, and also cultural monuments, such as churches and castles are collected during the course of the project.