German Organization for International Cooperation GIZ / ECOserve. Our experts have created a portable energy audit device and developed an appropriate computer program (software) through which it is possible to measure the coefficient of thermal conductivity (λ) of any material or structural elements of a building (wall, roof, etc.), which allows to precisely determine the thermal resistance and, consequently, the heat transmittance coefficient (U-value) and heat losses, resulting in an accurate estimate of the actual energy efficiency level; A guidebook on energy efficiency and energy auditing has also been developed;