Efficiency analysis of flat plate collectors for building facade integration

A theoretical approach has been used to evaluate the performance of facade integrated solar collectors based on the physical collector parameters such as absorber plate absorptance, transmittance of the glazed cover plate and insulation thickness. A 1D steady state model, based on the Hottel Whillier Bliss equation, was employed to determine the effect of changing parameters to meet façade integration criteria.

Voir Hitler en peinture

Voir Hitler en peinture / On Seeing a painting of Hitler
The article “Voir Hitler en peinture” (literally “On Seeing a painting of Hitler”) focuses on a painting by Oliver Jeffers entitled “Ginger Hitler”. This article suggests that, whatever Jeffers’ intent and inspiration were, his painting “defamiliarizes” Hitler (V. Shklovsky) and forces us to look at him afresh. For decades, Hitler has been demonised and dehumanised; yet, however unsettling this may be, he was human. As Professor Richard Evans, a leading expert in the history of Nazism, put it recently: “Viewing Hitler as a human being, which he undoubtedly was, is more challenging to our understanding, surely, than simply writing him off as a cartoon villain” (The Guardian, 30/04/2015).

Experimental investigation of thermal inertia properties in hemp-lime concrete walls

Hemp-lime concrete is a sustainable alternative to standard building wall materials, with low associated embodied energy. It exhibits good hygric, acoustic and thermal properties, making it an exciting, sustainable building envelope material. When cast in temporary shuttering around a timber frame, it exhibits lower thermal conductivity than concrete, and consequently achieves low U-values in a primarily mono-material wall construction. Although cast relatively thick hemp-lime walls do not generally achieve the low U-values stipulated in building regulations. However assessment of its thermal performance through evaluation of its resistance to thermal transfer alone, underestimates its true thermal quality. The thermal inertia, or reluctance of the wall to change its temperature when exposed to changing environmental temperatures, also has a significant impact on the thermal quality of the wall, the thermal comfort of the interior space and energy consumption due to space heating. With a focus on energy reduction in buildings, regulations emphasise thermal resistance to heat transfer with only less focus on thermal inertia or storage benefits due to thermal mass. This paper investigates dynamic thermal responsiveness in hemp-lime concrete walls. It reports the influence of thermal conductivity, density and specific heat through analysis of steady state and transient heat transfer, in the walls. A novel hot-box design which isolates the conductive heat flow is used, and compared with tests in standard hot-boxes. Thermal diffusivity and effusivity are evaluated, using experimentally measured conductivity, based on analytical relationships. Experimental results evident that hemp-lime exhibits high thermal inertia. They show the thermal inertia characteristics compensate for any limitations in the thermal resistance of the construction material. When viewed together the thermal resistance and mass characteristics of hemp-lime are appropriate to maintain comfortable thermal indoor conditions and low energy operation.