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Optical properties (i.e. reflectance, transmittance, etc) of light scattering materials can be described using two approaches.The first approach, models the interaction of light with the matters particles (microscopic approach), while the second, models the light fluxes into and out of bulked considered matter (macroscopic approach). Kubelka-Munk (K-M) is the most common theory of macroscopic modeling, for calculating the change of light fluxes (two-flux theory) as a function of scattering, absorption, and distance.

During the last years there is an increased consciousnessof the environmental problems, which are created by the use of fossil fuels for electrical power generation consumed by converting cooling systems. In addition, the use of common working fluids (refrigerants), with their ozone-depleting and global warming potential, has become a serious environmental problem.

One of the research areas of the Energy research Centre of the Netherlands (ECN) concerns the built environment.Several facilities to conduct the research activities are at ECNs disposal. One of these facilities, are five research dwellings located on the terrain of ECN. Measureddata from these facilities together with weather data and computer models are used to evaluate innovativeenergy concepts and components in energy systems on their performance.

The design of sustainable cities in locations with adverseclimates should consider different ways to mitigatethe heat in open spaces, especially during the summerperiods. One of the passive strategies to improve the thermal conditions of places with warm and dry climate is the use of evaporative systems. The Europeanproject ECO-Valle Mediterranean Verandahways was created with this aim, looking for the conditioning of open spaces by means of natural techniques and the reduction of CO2 emissions.

The relation between skins as metabolisers and the innercontent of different bodies will be discussed.Examples from the world of plants will illustrate how plants respond to their fixed environment and their fixed supply of water and nutrients.Examples from the world of animals will illustrate that even though animals are mobile they respond in general classification terms to their natural habitat.The tremendous versatility of the skin of the human beingwill be presented.The response of different skins to seasonal adaptation and the element of time will be discussed.The above will be correl

Real-time control of comfort in indoor spaces needs models of temperature distribution and air-velocity velocityfield. Complete models, based on CFD, give this information but are improper for real-time calculations. Therefore, a reduced model is needed. This study proposesto reduce the dimension of a CFD model by first considering the velocity field fixed and solving only the energy balance equation, then putting this equation in the form of state-space and finally by reducing its orderby Proper Orthogonal Decomposition (POD).

High reflective coatings and paintings for the building envelope can be very useful to reduce the cooling loads and ensure thermal comfort conditions in the built environment.A sustainable painting obtained with a specialmixture of milk and vinegar is able to reach very high solar reflectance for light colours and especially for the bright white was tested during summer 2006 and used for roofs and walls for several purposes. The solar reflectance of this materials and of usual construction materials was measured with a spectrophotometer.

The main decisions concerning thermal comfort and energyefficiency of buildings are made in the early stages of the architectural design. Common practice relies on general indications based on climate analysis and heuristicrules about orientation, thermal mass and so forth. Such an approach usually demands assessment by simulation,deriving in an empirical process of check and see. Another approach would be to think of the building as an adaptive system with a potential to ensure thermal comfort.

Despite the available knowledge about technologies for passive cooling, cooling energy consumption is still increasing in Europe. The international project KeepCooladdressed this gap, searching for intelligent ways to promote the market penetration of passive cooling solutions.

Five most commonly used single span shapes of greenhousesviz. even-span, uneven-span, vinery, modified arch and quonset type have been selected for comparison.The length, width and height (at the center) is kept same for all the shapes. Total solar radiation input (beam, diffused and ground reflected) to each shape (through each wall, inclined surfaces and roofs) is theoreticallycomputed for east-west and north-south orientationsand compared for each month of the year at 31 N latitude.