In many Least Developed Countries, the minimum level for basic services like energy access is not reached. In the cases of long-term investment in carbon intensive technologies, the expansion of basic services is likely to carry with it a significant increase in GHG emissions. This chapter discuss the importance of accounting for these avoided emissions through the case study of the Passive Solar Houses (PSH) in Afghanistan. In Kabul winters are cold and 48 % of households cannot afford enough fuel to heat their house. To reduce fuels expenses and improve living conditions, the NGO GERES is supporting local artisans to disseminate a PSH model made of a veranda built on the south-facing part of the house to conserve the sun energy captured and stored in the walls. During the 2013-2014 winter, the fuel consumption and indoor temperature of PSH and control houses were monitored to assess the impact of the technology. The results show an energy saving of 23 % resulting in annual greenhouse gases emission reduction of 0.37 tCO 2 e/year as well as an average indoor temperature increase of 1.43 C to reach 18.22 C. Then, a regression model was developed to estimate the emissions that would have occurred if the control group had reached the same indoor temperature than the PSH and, in a second scenario, the minimum indoor temperature of 18 C recommended by the WHO. For both scenario, the avoided emission represent approximately half of the total climate change mitiga-tion impact with 0.40 tCO 2 e/year and 0.34 tCO 2 e/year respectively.