In European countries, buildings are the major energy consumers due to the general low energy performance of the existing building stock. To achieve the ambitioned targets for emissions reduction, it will be necessary to take actions for its large scale renovation. However, today's standards are mainly focused on new buildings, guiding the improvement of the energy performance of the existing buildings into expensive processes and complex procedures that seldom are accepted by users, owners or promoters.

A new analysis framework is developed and applied to assess the benefits of building energy efficiency policies and programs. One of the main advantages of the new energy productivity analysis is that it accounts for both economic and energy performances of energy efficiency actions using only one metric. Specifically, the approach applies the concept of energy productivity to the building sector and accounts for both value added and energy savings of energy efficiency measures.

The German government has developed a variety of policy instruments intended to reduce national CO2 emissions. These instruments include a programme administered by KfW bank, which aims at improving the energy efficiency of buildings. It provides attractive credit conditions or subsidies to finance refurbishment measures which improve the energy efficiency of buildings significantly. The refurbishment programme leads to a reduction in energy use, which benefits private investors by reducing their energy bills.

Contemporary societies are facing a broad range of challenges, from pressures on human health and well-being to natural capital depletion, and the security of food, water and energy. These challenges are deeply intertwined with global processes, such as climate change and with local events such as natural disasters. The EU's research & innovation (R&I) policy is now seeking to address these challenges from a new perspective, with Nature-Based Solutions, and turn them into innovation opportunities that optimise the synergies between nature, society and the economy.

Pursuing economic targets of job creation, growth, and innovation while tackling global environmental challenges, has long been seen as impossible. However, any long-term economic competitiveness and security depends on the extent to which natural resources are used sustainably. Therefore, the European Union is investing in nature-based solutions to achieve this double goal. The difference between the prevailing economic model and a sustainable resource use has long seemed insurmountable.

Nature has provided humankind with food, fuel, and shelter throughout evolutionary history. However, in contemporary cities, many natural landscapes have become degraded and replaced with impermeable hard surfaces (e.g., roads, paving, car parks and buildings). The reversal of this trend is dynamic, complex and still in its infancy. There are many facets of urban greening initiatives involving multiple benefits, sensitivities and limitations.

Nature-based solutions (NBS) are increasingly applied to guide the design of resilient landscapes and cities to enable them to reach economic development goals with beneficial outcomes for the environment and society. The NBS concept is closely related to other concepts including sustainability, resilience, ecosystem services, coupled human and environment, and green (blue) infrastructure; however, NBS represent a more efficient and cost-effective approach to development than traditional approaches.

Increasing urbanisation, changing disease scenarios, and current predictions of climate change impacts require innovative strategies for providing healthy and sustainable cities, now and in the future. The recently coined concept, Nature-based solutions (NBS), is one such strategy referring to actions that are inspired by, supported by, or copied from nature, designed to address a range of environmental challenges.