Johannesson, G.
Bibliographic info:
The 6th International Conference on Indoor Air Quality, Ventilation & Energy Conservation in Buildings IAQVEC 2007, Oct. 28 - 31 2007, Sendai, Japan

The present paper deals with modeling of various low-exergy system components and their integrationinto the energy system for buildings and small communities. The exergy content of a certain amount ofenergy is defined as the part of this energy that can be used to produce mechanical energy. The qualityof a certain amount of energy is defined as the relative exergy content of this energy. Most of ourbuildings with their heating and cooling systems today are built for conversion of high quality energysources to low quality use with a huge destruction of the available exergy as a result. Globally we havea huge potential for transforming our processes to more efficient use of the exergy and also for feedingour processes directly from renewable energy sources without the use of high quality energy sources.To develop our building concepts towards a low exergy building we have to analyze all the processesfor energy conversion that take place through the operation of the building, to bring down the neededlevel of quality for the energy used and then make a holistic analysis of the system. Different processesfor energy conversion in buildings are discussed especially giving the potential for saving energy andshifting the energy use to lower quality levels, i.e. in many cases to reduce the temperature levelsneeded for heating and cooling. The major obstacle for an extensive and effective use of renewableenergy sources is the investment needed to be able to store heating and cooling energy in time. Thepaper gives a system concept under evaluation were the ground under the floor slab on grade is usedas heat reservoir for the building. The main advantage of the system would be lower investment costand at the same time give possibilities more effective annual storage compared to a single borehole.The paper also exemplifies how recent finite element technology where multiple physical phenomenacan be studied simultaneously can be utilsed for design of low exergy components.