System Design and Energy Performance of Ventilation Systems in Small Residential Buildings: A Comparison Study of FTX-Ventilation and Termite Ventilation with Demand and Seasonal Controlled Ventilation

Abstract

Ventilation is one of several subsystems that are necessary for a building to function as intended from an indoor climate and energy point of view. FTX-ventilation are advocated in low-energy buildings, both from an energy and indoor climate perspective. Some actors in the industry claim that Termite ventilation in combination with demand and seasonal controlled ventilation is to be equally energy efficient as FTX-ventilation and provides a better indoor climate, but with less technology and installations. This study has evaluated and compared system design and energy performance of Termite ventilation and FTX-ventilation with demand- and seasonal controlled ventilation in small residential buildings, with regard to ensuring a good indoor climate. A case study has been done where a literature review and energy calculations have been applied to an ongoing housing project. The study shows that exhaust air ventilation with ground duct (FK-ventilation) is a suitable type of Termite ventilation for small residential buildings. Both a FK- and FTX-system ensure a good indoor climate if designed, operated and maintained correctly and if seasonal controlled ventilation is used. A FTX-system is though known to be noisier. The energy performance largely depends on the choice of heat exchanger for a FTX-system and choice of heating system. The energy demand of a FTX-system during heating season is more than 50 % lower than a FK-system but when using a heat pump it is about the same. A FTX-system with plate heat exchanger and a FK-system has about the same power demand meanwhile a FTX-system with rotary heat exchanger has about 50 % lower. The energy demand is not the decisive factor in the choice of ventilation system, if using a heat pump. Then there are other indicators that determine the choice of system such as power demand, maintenance, user-friendliness, indoor climate, cost, etc.