The energy consumed to condition fresh air is considerable, particularly for the buildings such as cinema, theatre or gymnasium saloons. The aim of the present study is to design a ventilation system assisted with exhaust air heat recovery unit, electrical heater and stored solar energy, then to make an economical analysis based on life cycle cost (LCC) to find out its payback period. The system is able to recover thermal energy of exhaust air, store solar energy during the sunlight period and utilize it in the period between 17:00 and 24:00 h. The transient behaviour of the system is simulated by the TRNSYS 16 software for winter period from 1st of November to 31st of March for lzmir city of Turkey. The obtained results show that the suggested ventilation system reduces energy consumption by 86% compared to the conventional ventilation system in which an electrical heater is used. The payback period of the suggested system is found to be 5 years and 8 months which is a promising result in favour of the solar energy usage in building ventilation systems. (C) 2013 Elsevier B.V. All rights reserved.