Simple model and control strategy of earth-to-air heat exchangers
The worldwide energy situation forces industrialized countries to reduce their energy consumption, especially in the building sector, which makes up a high proportion of the total consumption. Techniques such as earth-to-air heat exchangers must therefore be developed and managed to meet this challenge. Yet earth-to-air heat exchangers provide better performance when linked to efficient control strategies.
Re-inventing air heating: Convenient and comfortable within the frame of the Passive House concept
Abstract Buildings complying with the Passive House standard are rapidly spreading across Germany, Austria and Switzerland. The underlying Passive House concept is based on a holistic approach, improving the building envelope to a degree that allows for substantial simplifications of the heating system. Passive Houses offer increased comfort at affordable costs while significantly reducing the energy consumption. The useful energy required for space heating has been reduced by ca. 80% compared with conventional (new) buildings. The overall primary energy consumption (including all services and electric appliances) has been reduced by more than 50%. Our paper introduces the Passive House standard and summarizes results of the EU project ‘Cost Efficient Passive Houses as European Standards’ (CEPHEUS) with respect to energy indices and comfort. Characteristics of the combined ventilation and heating system realized in many Passive Houses are presented in detail, including results of an expert working group at the Passive House Institute and on measurements and simulations conducted at EMPA. Chances and limitations of wood stoves as supplementary heat sources in Passive Houses are discussed shortly.
Optical rotatory dispersion and absolute configuration—III
Abstract Optical rotatory dispersion measurements on pyrrolidine, piperidine, and tetrahydro-isoquinoline alkaloids indicate that the absolute configuration of the α-asymmetric center may be assigned directly from the dispersion curve, provided either that the nitrogen atom is not protonated, or that the compound contains a chromophore absorbing above 200 mμ.