Without control high solar fractions arc difficult to obtain from Trombe walls, direct solar gains, and rock bins. Integration of all these techniques by control is absolutely necessary. A short review is given of the available sensors, actuators, and control systems. The control of individual solar techniques as well as several combinations are discussed; for instance, the control strategy for the combination of direct solar gains and Trombe Wall. Based on literature general conclusions are given about the energy efficiency of these systems in relation with the control strategy.
The 1995 edition of the National Building Code of Canada has extensively changed the ventilation requirements for housing. The code includes detailed prescriptive requirements, because in the past ventilation system design and compliance has varied. In this piece we are focusing on the new requirements in the National Building Code. These requirements apply in all areas except for Ontario and B.C. where provincial requirements were modified several years ago, and will be continued with only minor modifications.
The requirements to know indoor thermal comfort ask for a more detailed study of room temperature responses. Although CFO (Computational Fluid Dynamics) techniques can be applied successfully to the prediction of indoor temperature distributions, using them for the dynamic calculation of temperatures and air flows is still a very expensive expenditure. For indoor climate control systems, it is necessary to make quick calculations of the dynamic temperature distributions in a room.
Heat recovery is difficult to implement in passive stack ventilation because the pressure loss is usually too high in conventional heat exchangers compared with the stack pressure. Laboratory investigation and computer simulation have been carried out on a low pressure-loss heat recovery device based on heat pipes which is suitable for application in passive stack systems and other systems where a low pressure loss is essential. It was found that heat recovery efficiency decreased with increasing air velocity.
To control the indoor thermal environment within the comfortable range, the dynamic temperature distributions and flows of room air must be correctly predicted. While the CFO (Computational Fluid Dynamics) technique can be used to carry out such a prediction task, its drawback is also obvious: too time-consuming. To solve this problem, the dynamic temperature distributions can be predicted with some fixed air flow fields calculated with CFD codes. That is, sacrifice the dynamics of indoor air flows and only preserve the dynamics of the temperature distributions.
The thermal performance of the underground airpipe air conditioning system constructed at the Non-Conventional Energy Research Institute, Ghosi has been studied. The heat exchanger is used in recirculation mode to aircondition eight rooms in a guest house at the Institute. The temperature and relative humidity of a conditioned and non-conditioned room are measured every two hours. The cooling potential of the system is estimated. It is observed that reasonably good thermal comfort conditions can be created in the building with such a system.
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