The influence of relative humidity on adaptive thermal comfort

Buildings generate nearly 30% of global carbon emissions, primarily due to the need to heat or cool them to meet acceptable indoor temperatures. In the last 20 years, the empirically derived adaptive model of thermal comfort has emerged as a powerful alternative to fixed set-point driven design. However, current adaptive standards offer a simple linear relationship between the outdoor temperature and the indoor comfort temperature, assumed to sufficiently explain the effect of all other variables, e.g. relative humidity (RH) and air velocity. The lack of a signal for RH is particularly surprising given its well-known impact on comfort. Attempts in the literature to either explain the lack of such a signal or demonstrate its existence, remain scattered, unsubstantiated and localised. In this paper we demonstrate, for the first time, that a humidity signal exists in adaptive thermal comfort using global data to form two separate lines of evidence: a meta-analysis of summary data from 63 field studies and detailed field data from 39 naturally ventilated buildings over 8 climate types. We implicate method selection in previous work as the likely cause of failure to detect this signal, by demonstrating that our chosen method has a 56% lower error rate. We derive a new designer-friendly RH-inclusive adaptive model that significantly extends the range of acceptable indoor conditions for designing low-energy naturally-conditioned buildings all over the world. This is demonstrated through parametric simulations in 13 global locations, which reveal that the current model overestimates overheating by 30% compared to the new one

Probabilistic adaptive thermal comfort for resilient design

Adaptive thermal comfort theory has become the bedrock of much thinking about how to judge if a free-running environment is suitable for human occupation. In design work, the conditions predicted by a thermal model, when the model is presented with one possible annual weather time series (a reference year), are compared to the limits of human comfort. If the temperatures are within the comfort limits, the building is judged to be suitable. However, the weather in many locations can vary year-on-year by a considerable margin, and this begs the question, how robust are the predictions of adaptive comfort theory likely to be over the many years a building might be in use? We answer this question using weather data recorded for up to 30 years for locations within each of the five major Köppen climate classifications. We find that the variation in the annual time series is so great that the predicted comfort temperature frequently lies outside the acceptable range given by the reference year. Return periods for the excursions of the time series are calculated for each location. The results for one location are then validated using the world's longest temperature record. These results suggest that industry and academia would be best advised to move to a probabilistic methodology, like the proposed one, when using adaptive comfort theory to judge the likely conditions within a building. Extra pertinence is provided by concerns over increases in mortality and morbidity in buildings due to a rapidly warming climate

Electrically Detected Magnetic Resonance of Donors and Interfacial Defects in Silicon Nanowires

We report our work on the characterization by electrically detected magnetic resonance (EDMR) measurements of silicon nanowires (SiNWs) produced by different top-down processes. SiNWs were fabricated starting from SOI wafers using standard e-beam lithography and anisotropic wet etching or by metal-assisted chemical etching. Further oxidation was used to reduce the wire cross section. Different EDMR implementations were used to address the electronic wave function of donors (P) and to characterize point defects at the SiNWs/SiO(2) interface. The EDMR spectra of as produced SiNWs with high donor concentration ([P]= 10(18) cm(-3)) show a single line related to delocalized electrons. SiNWs produced on substrates with lower donor concentration ([P] < 10(16) cm(-3)) reveal the doublet related to substitutional P in Si, as well as lines related to interfacial defects such as Pb(0), Pb, E', and E'-like. The EDMR spectra of samples produced by metal-assisted chemical etching exposed to post production oxidation reveal a disordered and defective interface and the disappearance of the P related signal. Forming gas annealing, on the other hand, reduces the contribution of interfacial defects and allows a better resolution of the P related doublet

Bridging the gap from test rooms to field-tests for human indoor comfort studies: A critical review of the sustainability potential of living laboratories

Occupants play a key role in determining final building energy consumption. Empirical evidence must support occupants’ modelling. Experiments on human responses to Indoor Environmental Quality (IEQ) are usually performed in test rooms or as in-field monitoring. Between these two approaches, living laboratories, often abbreviated as living labs, represent a valid alternative due to their resemblance to real-world settings. This allows observing actual behaviours while keeping the capability to reliably monitor and control the indoor environment. This work systematically reviewed the available information from 34 living labs for human comfort studies worldwide to define the scope, characteristics, and significance of living labs, for the first time. Most of the reviewed living labs are office environments, and only a few do not involve a university research institution in their operation and management. Most of them are in Europe and the United States, whereas there is a lack of such facilities in other locations and climate zones (e.g., tropics). A larger number of comfort studies in living labs is required to clarify the differences in the knowledge acquired in these experiments compared to in-field and laboratory ones. The review shows that living labs add opportunities for testing and optimizing innovations in human-centric solutions for comfortable green buildings. Through the living labs approach it is possible to holistically capture the influence of IEQ on occupant perception and the related response, to gather data on larger and more diverse groups of people, and to conduct multi-domain comfort studies involving multidisciplinary approaches given their real-life settings