Historic and heritage buildings present a significant challenge when it comes to reducing energy consumption to mitigate climate change. These buildings need careful renovation and increasing their energy efficiency is often associated with a high level of complexity, since consideration for heritage values can often reduce and impede possibilities and sometimes even rule out certain im-provements completely. Despite these issues, many such renovation projects have already been carried out, and therefore the IEA SHC Task 59 project (Renovating Historic Buildings Towards Zero Energy) in cooperation with Interreg Alpine Space ATLAS has developed a tool for sharing these best-practice examples – the HiBERatlas (Historical Building Energy Retrofit Atlas). The In-ternet platform serves as a best-practice database of both individual energy efficiency measures and whole-building renovation projects. This paper presents two of the Danish projects featured in HiBERatlas. The first project, Ryesgade 30, is a Copenhagen apartment building with a preser-vation worthy period brick façade. The second project is the Osram Building, a listed Copenhagen office building from 1959 with a protected façade, which today acts as a culture centre. Both renovation projects achieved significant energy savings and consequently CO2-emission reduc-tions, and the indoor climate in both buildings have also improved significantly. Furthermore, a detailed analysis was carried out regarding possible window solutions and ventilation systems in Ryesgade 30, and for the Osram Building regarding daylighting technologies. The paper investi-gates the two renovation cases through the available measurement and calculation results before and after renovations and demonstrates that it is possible to reduce energy consumption signifi-cantly and at the same time improve the indoor climate without compromising the cultural values of the buildings. ; Historic and heritage buildings present a significant challenge when it comes to reducing energy consumption to mitigate climate change. These buildings need careful renovation and increasing their energy efficiency is often associated with a high level of complexity, since consideration for heritage values can often reduce and impede possibilities and sometimes even rule out certain im-provements completely. Despite these issues, many such renovation projects have already been carried out, and therefore the IEA SHC Task 59 project (Renovating Historic Buildings Towards Zero Energy) in cooperation with Interreg Alpine Space ATLAS has developed a tool for sharing these best-practice examples – the HiBERatlas (Historical Building Energy Retrofit Atlas). The In-ternet platform serves as a best-practice database of both individual energy efficiency measures and whole-building renovation projects. This paper presents two of the Danish projects featured in HiBERatlas. The first project, Ryesgade 30, is a Copenhagen apartment building with a preser-vation worthy period brick façade. The second project is the Osram Building, a listed Copenhagen office building from 1959 with a protected façade, which today acts as a culture centre. Both renovation projects achieved significant energy savings and consequently CO2-emission reduc-tions, and the indoor climate in both buildings have also improved significantly. Furthermore, a detailed analysis was carried out regarding possible window solutions and ventilation systems in Ryesgade 30, and for the Osram Building regarding daylighting technologies. The paper investi-gates the two renovation cases through the available measurement and calculation results before and after renovations and demonstrates that it is possible to reduce energy consumption signifi-cantly and at the same time improve the indoor climate without compromising the cultural values of the buildings.