Characterisation of the flexibility potential from space heating in French residential buildings

Demand response (DR) at the building level (also named energy flexibility) will play an important role in facilitating energy systems based mostly or entirely on renewable energy sources. Flexibility is thus deemed necessary to control the energy consumption to match the actual energy generation from various renewable energy sources such as solar and wind power. However, there is lack of comprehensive knowledge about how much energy flexibility different building types and their usage may be able to offer to the present or future energy systems. In this study, the flexibility potential of space heating is characterised among the building stock in France. Five different typologies of buildings were chosen (post-1945, BR 1982, BR 2005, BR 2012 and BR 2020) with different levels of insulation, air-tightness and thermal mass. Building energy simulations were performed, with modulations (i.e. increase or decrease) of the space heating set-point during the heating season. From this study, the large influence of the envelope properties on the flexibility potential was highlighted: the storage efficiency for upward modulations and the rebound rates for downward modulations range from 40% up to 90% in poorly insulated and well-insulated buildings, respectively. This study describes a generic method and provides quantitative data to estimate the flexibility potential for demand response at the building level and to help designing future energy grids

Hydrocarbon influence on denitrification in bioturbated Mediterranean coastal sediments

An in situ experiment has been carried out inbioturbated Mediterranean coastal marine sediments (Gulfof Fos) in order to study the influence of hydrocarbons ondenitrification after 1, 4 and 6 months. In theabsence of hydrocarbons in the control sediments, the presenceof macrofauna stimulated denitrificationby 160%. This stimulation is induced by sediment reworkingthat favours both direct NO-3 supply fromthe water column and the penetration of O{2}, which in turnstimulated nitrification, the other source ofNO-3 in sediment. The presence of hydrocarbons in theexperimental sediments either stimulated orinhibited the denitrification. The denitrification response tothe presence of hydrocarbon is dependent onthe quantity of matter buried by the macrofauna activity. Insmall quantities, the organic matter relatedto hydrocarbons 120% enhanced the denitrification compared tothe controls. On the other hand, whenburied hydrocarbon concentrations were higher (>100 mgsaturated hydrocarbon fraction kg-1 drysediment), the denitrification was inhibited.On the basis of the results obtained, a descriptive model ofthe patterns of denitrification in relation to the presence ofmacrofauna and the distribution of hydrocarbons in sediments is proposed

Computational analysis of energy and cost efficient retrofitting measures for the French house

Energy-efficient housing has become a mandatory aim to address climate change. This paper presents a computational analysis taking a French single family house as a case study, and aims to investigate both energy and cost-efficiency of market available retrofit measures using dynamic thermal modelling. A parametric analysis tool was developed to run automated batch-simulations using EnergyPlus simulation engine and to calculate the cost associated with retrofit measures, at each simulation run. The automated simulations are carried out, using an exhaustive search technique, for all permutations of measures. These included different building fabrics, ventilation strategies, levels of air-tightness and 5 different heating systems for 4 main climatic regions of France (7680 variants for each of the 4 climatic region). In this analysis, an optimization problem is set to minimise the delivered energy and retrofitting investment cost subject to an energy-saving minimum limit, payback criterion, and summer overheating-risk. The results showed optimum solutions with different fabric and system retrofit combinations that varied in numbers for the different climatic zones. The upper bound of optimum investment cost varied from 80 to 290 €/m2 for Nice and Paris, respectively

Jagged2 controls the generation of motor neuron and oligodendrocyte progenitors in the ventral spinal cord

In the developing spinal cord, motor neurons (MNs) and oligodendrocytes arise sequentially from a common pool of progenitors. However, the genetic network responsible for this neurogenesis to gliogenesis switch is largely unknown. A transcriptome analysis identified the Notch ligand Jagged2 (JAG2) as a Sonic hedgehog-regulated factor transiently expressed in MN progenitors (pMNs). In vivo loss- and gain-of-function experiments show that JAG2 schedules the differentiation of the pMN progenitors. At early developmental stages, Olig2 expressing pMN progenitors that enter the differentiation pathway exclusively generate MNs. At these times, the activation of the Notch pathway by JAG2 maintains selected pMN progenitors in an undifferentiated state by two mechanisms; first it inhibits MN generation by reducing Olig2 proteins levels, and second it directly inhibits the premature generation of oligodendrocyte progenitors (OLPs) by maintaining high levels of Hes5. Later, extinction of JAG2 from the pMN results in the loss of Hes5 expression, heralding the gliogenic phase of pMN progenitors. Strikingly, downregulation of JAG2 in pMN progenitors is sufficient to promote the precocious generation of OLPs. Together these data provide evidence that JAG2 is a key regulator of the timely and ordered generation of two of the defining cell types in the spinal cord, MNs and OLPs