The current state of the art approach for more efficient in buildings is based on the use of following materials and technologies:
1.thermal insulation materials,
2.efficient heating and cooling systems,
3.better ventilation and
4.integration of RES.

Efforts to demonstrate energy efficient buildings are affected by higher construction costs (1; 2; 4),
problems to adapt the solutions to different scenarios (1;2;3;4), system maintenance costs (2;4), and
also lack of knowledge in the management of the technologies for an optimum operation (2;3;4).

Current approaches aim mainly at energy reduction, and cannot conceptually target “energy self-sufficiency of a building” in cost and performance. The latter can be achieved through an integrated approach that combines building design with energy storage systems which could adapt their performance to the climatic conditions and energy demand of the building.
New tendencies in construction go trough lightweight buildings with well insulation materials distribution.
The thermal inertia of these buildings has been reduced. So, it becomes urgently necessary to compensate it by thermal storage systems.
From the utilities point of view, the state of the art in energy supply (generation, transmission, and distribution) is close to reach the upper limit in serving peak loads. Today, it is often impossible to meet energy needs without big investments in new infrastructures. The consequence is a lack of grid reliability, increased price, and the need of huge investment. The addition of energy storage to buildings is of utmost importance whether we plan to use power plants, renewals, or both, to make those buildings comfortable. Our 24-hour day and seasonal cycles sets the circumstances for storage.
The revolutionary new approach of MESSIB is to create buildings and districts with new energy storage capacities. With this approach MESSIB will permit:

• A reduction of the total energy demand, which allows end users to reduce and optimize energy consumption. The share of conventional energies (fossil fuels) of this demand will be reduced.
• The adaptation, management and regulation of the energy demand in buildings, not only considering the building and districts themselves, but in interaction with the grid, improving the reliability, quality and security, increasing the efficiency of the network and reducing the energy price and price volatility.

Thermal storage can take the form of sensible heat storage (SHS) or latent heat storage (LHS). To store the same amount of energy, significantly larger quantities of storage medium are required for SHS in comparison to LHS. In buildings this can be illustrated by the sensible heat capacity of concrete, which is approximately 1.0 kJ/kgK, whereas calcium chlorine, which during phase transition can store/release 190 kJ/kg of heat. Solar thermal storage systems in buildings can be a solution to the time-mismatch between the internal space heating demand at night and external solar energy available during the day. When LHS is used to store solar energy it can increase the thermal storage efficiency of the building reducing the total energy demand.
There is a social and economic interest in the application of storage technologies to houses and buildings of offices derived from the existing potential market at European level, where the forecast of the growth of bioclimatic buildings is very large. The advantage of this application is that, the concept of Distributed Storage will be introduced, accordingly with the concept of Distributed Generation. The problem of the energy storage is its limitation as far as power and especially to energy, not having comparable systems to the generation power plants. With MESSIB, it can be obtained a great potential of stored energy by breaking up the stored energy in small units (ready in buildings of house and offices). In this way, it is finally arranged a potential of stored energy, equipping to the system with a certain global capacity of adapting, managing and regulating the energy demand in the building.

On the other hand, considering the integration of this technology with the use of RES, this project arises from the necessity of a more efficient energy management consuming less conventional energy. Nowadays, large amount of resources are wasted because of the fact that it is not being able to store the non-use energy at the moment of their production. That is, at present there is no possibility of using the generated energy after its production. On the contrary, the generated energy is used or is lost. But this fact, frontally clash crashes head on with the philosophy of the RES. That is the reason why ACCIONA and the rest of the MESSIB consortium are setting out alternatives to solve this problem.