This paper aims to develop thermal model of a vault roof building integrated with earth to air heat exchanger (EAHE). The building under consideration is made of brick vault and adobe (or mud) structures. The methodology adopted for developing thermal model of this building with six interconnected rooms is presented ill this paper. The energy balance equations were solved simultaneously Using fourth order Runge-Kutta numerical technique. The results from the thermal model were validated using experimental observed data. Experimental results showed that the room air temperature during winter was found 5-15 degrees C higher as compared to ambient air temperature while lower during Summer months. The results show that annual energy saving potential of the building before and after integration of EAHE were 4946 kWh/year and 10321 kWh/year respectively. The seasonal energy efficiency ratio (SEER) for EAHE was determined as 2-3. This considerable increase in annual energy savings potential of building due to EAHE leads to mitigration of CO2 emissions about 16 tons/year and the corresponding annual carbon credit of building was estimated as (sic) 340/year. The life cycle cost (LCC) analysis shows that the payback period is less than 2 years for the investment on EAHE system. (C) 2008 Elsevier B.V. All rights reserved.