This paper investigates energy conservation, mitigation of CO2 emissions and economics of retrofitting for a honey storage building with Trombe wall for winter heating application. The passive heating potential of Trombe wall for a honey storage building was estimated using TRNSYS building simulation software. This honey storage building is located at Gwalior (latitude: 26 degrees 14'N) in India. During winter months, the room air temperature of building falls below the required temperature range of 18-27 degrees C which is suitable for honey storage. So, the room air temperature range is maintained in the building using a 2.3 kW capacity electrical oil filled radiator (or room air heater) which accounts for the major energy consumption of the building on an annual basis. On account of which there are significant CO2 emissions into the atmosphere from the honey storage building. Hence, this case study was conducted to recommend the passive heating concept to the stakeholders of the building so as to conserve the energy requirement for room air heating. The investigation showed that the room air temperature can be easily maintained in the range suitable for honey storage using a vented Trombe wall. The experimental work was carried out for the existing building on a typical clear day of harsh winter month of January to validate the results of TRNSYS model of the present building. The statistical error analysis showed a good agreement between model and experimental results. This investigation concludes that there is potential of energy conservation up to 3312 kWh/year and associated reduction in CO2 emissions (similar to 33 tonne/year) using a Trombe wall. Also, the retrofitting of building is economically viable as the simple payback period is only about 7 months. (C) 2008 Elsevier B.V. All rights reserved.