dynamic insulation

To realize the concept of low-energy buildings, an increase in the thermal insulation performance of building parts, especially the openings that show poor insulation performance, is necessary. In addition, an adequate level of thermal comfort is also needed within residential buildings. We have developed window-applied dynamic insulation (DI), and verified thermal insulation performance in chamber and field tests.

An efficient thermal insulation of glazing or window frame is important because poor insulating performance usually cause the largest heat loss on any buildings. As one of the methods decreasing heat loss of buildings, we proposed a dynamic insulation system applied to window frame, and its energy saving performance and applicability for buliding had been confirmed using numerical simulation in previous study [1].

It is essential to reduce the inordinate amount of energy used for climate control in buildings. To reduce heat loss in residential buildings, it is necessary to insulate building envelopes more airtight. Many air tightness and insulation methods have been proposed and successfully applied to the building envelope, including areas such as walls, windows and the others. However, if it concentrates only air tightness and insulation to save energy consumption in the buildings, that’ll make a problem to maintain indoor air quality within acceptable levels, such as sick building syndrome.

This paper describes the energy-saving effects of the proposed system with an active ventilation function and a heat pump for heat recovery. First, the temperature of the air supplied through the porous material versus the outdoor temperature was calculated using computational fluid dynamics to set the boundary conditions for the energy simulation. Then, the cooling/heating loads of a typical residential building in Japan were calculated and comparisons were made with and without the proposed system installed.

In order to insulate buildings more efficiently, many insulation methods have been proposed and successfully applied to the building envelope, including areas such as walls and windows. However, it is also important to insulate window frames efficiently because they usually contribute the greatest heat loss. The authors propose a new dynamic insulation system for window frames, with an active ventilation function and a heat pump for heat recovery.

This paper presents an analysis of the transient thermal performance of dynamic insulation. A modelbased on heat transfer through porous media is introduced, considering two types of boundaryconditions: (1) indoor temperature and outdoor temperature are constant; (2) indoor temperature isconstant while outdoor temperature changes. By solving the model numerically, it is found that for thefirst kind of boundary condition, the temperature profile in the wall will reach steady-state within onehour, when the porosity is high.

Dynamic insulation is a very good example of a ventilation system integrated with the building envelope. The paper describes two recent studies carried out at Nottingham on dynamic insulation. One study concerns a system based on mechanical ventilation. The other describes a purely natural system. Although there are few existing applications of dynamic insulation, it is argued that there is potential for both systems, particularly with certain types of building. The natural system is technically more challenging than the mechanical system, but the potential energy savings are larger.