This paper investigates the design of space heating and ventilation to meet Code for Sustainable Homes (CSH) (CLG, 2008) targets for detached housing. The design of building services plant is radically affected by the requirements of the CSH. “Super insulated” u values and much "tighter" construction lead to fabric losses and uncontrolled ventilation rates that are considerably lower than those achieved by Building Regulation Approved Document L1A (ODPM, 2006). Before considering renewable technologies such as photovoltaics, designers should fully explore the potential of envelope and plant to achieve minimum CO2 emissions. Even with the most stringent envelope build quality it is not possible to meet CSH Level 3 without either triple glazing, solar thermal or mechanical ventilation with heat recovery. The CSH will require designers, builders and plant manufacturers to reconsider traditional envelope, heating and ventilation solutions.