In the present study, the cost-effectiveness and primary energy savings potential of various combinations of energy measures in newly constructed single- and multi-family house (SFH and MFH) buildings in two climate zones (B and C) in Greece are investigated. The calculations of the building loads and the investment and operating and maintenance costs of the measures are based on the methodology defined in the Directive 2010/31/EU. The economic assumptions were based on the EN 15459-1 standard. Natural gas boilers constitute the cost-optimal heating system for SFH buildings followed by low-temperature heat pumps, while the reverse is the case for MFH buildings. For both types of buildings, geothermal and low-temperature heat pumps exhibit the best energetic performance, followed by high-temperature heat pumps (in SFH buildings). Heat pump-based measures tend to be more cost-competitive when the heating/cooling loads are increased, which is the case for harsher winter climates and MFH buildings. Despite their high costs, photovoltaics are indispensable for reaching net zero energy building energy consumption levels, especially when coupled with heat pumps, due to the implementation of net-metering schemes. The partial upgrade of building envelope materials is also highly important. Notably, the current insulation specifications imposed by the Greek legislation lead to good economic and also energetic performance. The installation of solar assistance systems can be a very cost-competitive option in MFH buildings that are equipped with boilers. The financial gaps between cost-optimal and net zero energy building standards were calculated equal to 37-101 (sic)/m(2) and 6.3-133 (sic)/m(2) depending on the climate zone for SFH and MFH buildings, respectively. (C) 2019 Elsevier B.V. All rights reserved.