Switching from individual fossil fuel boilers to a district heating network not only allows the reduction of CO ₂ emissions but may also lead to significant reduction of other air pollutants such as SO ₂ , NO _x and PMx, which have well known negative effects on the human health. EvalCADair makes it possible to estimate the annual evolution of the emissions of atmospheric pollutants during the construction phase of a district heating network. This generic tool is applied to the case of the district heating network CADéco, whose heat production consists of centralized heat pumps and gas boilers. Located in Geneva, the case study includes 154 buildings with a total heated surface of 547’000 m ² and an annual heat demand of about 55 GWh. Approximately half of the total surface aera is dedicated to collective residential housing and the rest to various activities. By the end of 2022, 40% of these buildings were connected to the district heating network. Using the tool to estimate the emissions from 2011 to 2022 shows only a small reduction in CO ₂ emissions, mainly due to the replacement of individual oil boilers with centralized gas boilers. The gain will be more significant when the heat pumps will be activated. The future impact of the activation of the heat pumps is estimated using EvalCADair as a prospective tool.