The objective of this work is to quantify the resultant savings across the EU from the optimization of existing system components in domestic space heating distribution systems to maintain comfort levels. Heat energy savings are shown to range from 1% to 19% depending on dwelling type, age, location and initial specific heat energy consumption. Total potential savings across the sector amount 10 Mtoe, a reduction of 3.24 %; 87 % of these from a reduction in pumping power required by heating distribution systems and 13% of these from a reduction in the heat energy consumed by heating systems. The carbon abatement potential is estimated to be 27.2 million tonnes of CO2 equivalent. Regulatory changes to the domestic replacement and maintenance industry are required for these low-cost, high impact and highly applicable energy saving measures to be adopted more extensively.