Renewable systems for heating and cooling (RES-HC) systems in last ten years have gradually increased their importance and their presence in the global heating ventilation and air conditioning (HVAC) market. Many energetic analysis and impact assessments have been made, which have demonstrated the convenience, respect to traditional HVAC systems, of solutions such as solar thermal or low enthalpy geothermal systems in terms of: energy consumption reduction, renewable energy use increase and emissions decrease. However, the several analysis made, up to date, only have considered the operation period of such systems, and consequently the comparison has been made only in terms of energy vectors used, omitting materials, components and processes. This paper aims to give a new perspective, showing how a correct environmental analysis should take into account all the life cycle of a system, from the cradle to grave, also if the system concerns a renewable energy source. In the specific case, a Life Cycle Assessment (LCA) will be presented, focusing on two currently popular RES-HC systems: solar thermal and low enthalpy geothermal, compared to the same functional unit. The results of this analysis could be a good starting point for future work on impact assessment of more complex and integrated HVAC systems. © 2011 Published by Elsevier Ltd.