Compact ventilation appliances appeared on the market for solar passive houses. They include a heat pump to transfer heat from ventilation exhaust air to fresh air and/or domestic hot water. This article is the second part of a serie of two. It continues to describe a model for simulating the operation and performance of such appliances which was developped to be used in the TRNSYS software environment. It compares the results of calculations with those of laboratory measurements.
Dynamic simulation calculations were operated using TRNSYS software applied to a low energy house. This article is the second one of a serie of two. The first one was dealing with ventilation. This one mainly concerns heating system and domestic hot water production through a gas boiler. It also gives general conclusions, some of them dealing with ventilation.
Compact ventilation appliances appeared on the market for solar passive houses. They include a heat pump to transfer heat from ventilation exhaust air to fresh air and/or domestic hot water. This article describes such systems and gives information about a model for simulating the operation and performance of such appliances which was developped to be used in the TRNSYS software environment.
The Solar-Campus Juelich consists of two buildings, as part of the University of Applied Sciences, Aachen, and student dormitories for 136 students (5 row houses), see Figure 1. In a general agreement, the overall energy demand for space heating of all buildings was limited to 40 kWh/m 2 a, which is less than 50% of the existing German national regulation (Wrmeschutzverordnung 1995). Extra costs were provided through the AG Solar of the German state North-Rhine-Westfalia.
This contribution reports on investigations about the performance of decentralised ventilation units with heat recovery. Such units can be easily installed in individual rooms and therefore offer an interesting alternative to central ventilation units. Nevertheless these units exhibit some problems. Experimental examinations of two commercial decentralised units showed that the real effectiveness of heat recovery was always below 50 % and that considerable leakage between the air ducts can result in poor indoor air quality.
This paper presents an analysis of air-to-air total heat exchangers (heat and mass transfer) built up using moisture permeable paper (but impermeable to air molecules). Performance of 6 such total heat exchangers made of different types of paper were tested, in order to know their air leakage ratio and their energy saving ratio. An analysis is presented about the effect of leakage on energy recovery efficiency.
This study is an analysis of the advantages of two ventilation systems (exhaust mechanical ventilation, balanced mechanical ventilation with heat recovery) using the Negative Index approach, which is affected by life cycle cost and environmental impact. The balanced system appears to be a better choice (less environmental impact, better indoor air quality) even if its life cycle cost is higher.
The market evolution of domestic exhaust air heat pumps since 1979 in Sweden is described. Some information is also given about the German market. Technologies of different exhaust air heat pumps systems are shown and results of several monitoring projects in Sweden are summarized : they show for houses built in the 1980's an electricity consumption of 90 to 130 kWh/m2/year (including domestic hot water and household electricity), depending on the thermal characteristics of the building envelope. The energy savings thanks to the exhaust air heat pump are about 30%.