Background
There has been a lot of focus on energy efficient buildings recently, and there is a rapid development of new materials, construction methods and technologies on the market. Improvement of one product property may affect other aspects, for example the fire safety. Norwegian authorities want to get an overview of possible challenges associated with the fire safety of energy efficient buildings.

Objective
The main objective of this study has been to survey challenges associated with energy efficient buildings and fire safety, with a special focus on solar cells, batteries and fire extinguishment. The project is divided into different work packages. Sub-goals for each of these have been to:
• Study solar cell technology in the context of the total energy supply chain to uncover fire-related challenges. 
• Increase the understanding of safety challenges, solutions and regulations related to energy storage of batteries in buildings.
• Increase the understanding of challenges associated with fire extinguishment in energy efficient buildings where solar cells and/or batteries are used.
• Achieve an overall understanding of the interaction between different solutions in energy efficient buildings, and how these interactions affect the fire safety.

Conclusions
General
• The interaction between various new technical and energy efficient solutions could affect fire safety, with regard to ignition, fire development, fire dynamics, evacuation and firefighting efforts.
• When it comes to fire safety, questions often arise regarding what should be considered as sufficient and adequate documentation. Here, industry guidelines and exchange of knowledge is important, until relevant regulations are in place.
• It is important that fire safety is considered, and that responsibilities and tasks are coordinated when new solutions are implemented.
• The industry often feels that regulations are adapted too slowly when new solutions are launched.
• Our overall impression is that most professionals in the industry take fire safety seriously. Serious actors, good quality of design and installation are important to ensure a safe development.

Solar cells
• No substantial difference has been found in fire engineering challenges for large photovoltaic (PV) installations compared to small ones.
• Solar cells mounted on facades should be treated similarly to other facade claddings with cavities behind the cladding, with regard to fire testing and classification.
• The European regulations for fire testing of roofing materials are not well suited for testing of roofs with building attached photovoltaics.
• According to German statistics, building integrated photovoltaics have a significantly higher fire risk than building attached photovoltaics. However, this has not been thoroughly studied during recent years.
• It is primarily the electrical voltage that the solar cells generate that can be problematic for firefighting, including re-ignition hazard, shock hazard due to direct contact with energized components and through extinguishing water.

Batteries
• It is relatively well known how a fire in a battery may start, and this knowledge is transferable to stationary batteries in buildings.
• Lack of knowledge, experience and training within fire brigades with regard to large battery systems in buildings, may contribute to application of unfortunate extinguishing strategies.
• It is important that the fire service is informed when large battery systems are installed in buildings, to ensure that an extinguishing strategy exist in case of fire.
• In many cases, cooling with water is the best extinguishing method, but this can result in high water consumption as the battery itself supplies oxygen to the fire, and the battery encapsulation may prevent the water from reaching the fire zone.
• Regulations for domestic battery systems should be better defined with regard to placement and adequate safety levels. Guidelines for people who are considering installing battery systems in their homes would be beneficial.

Airtight buildings
• There is no substantial difference in the fire development in airtight and conventional buildings during the initial phases of the fire. According to fire modelling studies there are more pronounced differences at later stages of the fire. 
• The differences are mainly an increased pressure build-up and that the fire more rapidly becomes ventilation-controlled in airtight buildings. 
• There is also an increased risk of backdraft for fires in airtight buildings, which represents an increased risk for the firefighters.