Abstract

The building envelope plays a crucial role in reducing operational energy demand. In particular, the two main properties of the building envelope to look at in this perspective are thermal transmittance (U, W/m2K1) and thermal inertia, which is often expressed by a metric called periodic thermal transmittance (Yie, W/m2K1). These two properties are also traditionally connected to two different energy demands: while thermal transmittance is crucial to reduce heating energy demand, thermal inertia has an impact on energy demand for cooling. However, a question may rise about the impact of each property on the other demand – i.e. the impact of thermal insulation on the cooling energy demand and the impact of thermal inertia on the heating demand.
A parametric analysis on the influence of the thermal inertia on the energy performance of a single family house in a Nordic climate has been carried out to find an answer to this question. “Ideal envelopes” have been modelled and simulated, meaning that used thermophysical properties do not represent any configuration, but the entire spectrum of technological configurations.
The results show that the influence of the thermal inertia on the heating energy need is very limited. Even a relatively high value of Yie, which means no or little thermal inertia, does not determine a significant increase in energy need. Parallel to this, solutions characterized by very high thermal inertia do not allow heating energy demand to be sensibly decreased. Periodic thermal transmittance has instead an impact on the heating load. The impact of the thermal inertia is also assessed in the warmer season, and the results show that this parameter does not significantly contribute to a better behavior (especially when the upper limit of the indoor air temperature is controlled). Limitations to value of thermal transmittance are also pointed out to avoid non-energy effective conditions when the total (heating plus cooling) annual performance is considered.

Transparent façades are often used to increase the aesthetic value of the building and to provide visual contact with the outdoor. However, together with several positive features, it should be mentioned that glass façades may reduce the quality of the indoor thermal environment, causing thermal discomfort especially due to overheating in the summer season. The aim of this paper is to compare the implications on thermal comfort of different glazed façades, whose surface temperatures have been monitored during several experimental campaigns. The analyzed glazing systems were double skin façades and non conventional single skin façades integrating different materials (i.e. phase change material, areogel). Starting from the measured internal surface temperatures, a fictitious office room was simulated in order to assess the thermal comfort performance through the calculation of the PMV index. Results show that the choice of the glazing system can strongly affect the thermal comfort of an office.

Design principles in Net-ZEB considers the local energy infrastructure as virtual storage leading to large amount of energy exchange with the grid. Nonetheless, with high Net-ZEB penetration scenarios, such exchange could compromise the effectiveness of Net- ZEB concept in a total energy infrastructure. As the current market trends, heat pumps along with photovoltaics are seen as an emerging energy supply solutions in Net-ZEB buildings, effectiveness of an all-electric Net-ZEB (that is using air-to-water heat pump with photovoltaic) is analysed. Two concrete control cases of energy storage (compared to reference case) to assess Net-ZEB ability to self-consume vs. grid empowerment are studied. Results shows that introduc tion of storage buffer in such concept leads to a flexibility of almost 6 % in self-consumption and 13 % in grid-impact factor and in-turn provide significant manoeuvring space to the demand-supply balance at the grid level.

På Nanonkonferansen 18. mars 2013 var det speeddating med nanoforskere, som på 1 minutt presenterte nytt fra forskningsfronten. Klima- og forurensningsdirektoratet (Klif) og Forskningsrådet arrangerte konferansen for å belyse mulighetene og utfordringene som ligger i nanoteknologien.