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Insufficient ventilation is one of the main factors leading to damp and mould in residential buildings. One low-cost method to improve these moisture-related issues is positive input ventilation (PIV) but research data on performance is scarce in the literature. This paper presents a bibliographical review together with a case study based on monitoring a residential building by means of environmental sensors. The review reveals the importance of correct location, installation, operation and continued maintenance of mechanical ventilation systems. Specifically, PIV and exhaust ventilation units in existing buildings require routine checking to ensure these systems are working correctly and efficiently. The results of monitoring ambient and surface temperature and relative humidity show that the PIV and enhancement extract fan set-up can reduce atmospheric moisture levels and avoid surface condensation. Mould growth is no longer active, but it is always essential to perform thoughtful building inspections checking the right conditions for installation and maintenance to ensure the proper functioning of the units. It is critical to study the size of the building and structural characteristics of the roof and ceilings. Also to verify that the doors are well undercut to allow air flow and that the occupancy levels and regional climate are adequate for selecting the appropriate type of mechanical ventilation units and corresponding operational modes (flow rates, operational settings, etc.). More research, measurements and monitoring studies pre- and post-installation of PIV and other whole house mechanical ventilation systems are recommended to assess optimal performances. This could also help to ensure the success of retrofitting projects in residential buildings which aim to improve energy efficiency but also make buildings relatively airtight and prone to condensation damp. An effective, sufficient and appropriate ventilation system as well as a good installation practice and adequate maintenance is key to avoid surface condensation and mould growth and to improve the indoor air quality of both new and existing buildings. [ABSTRACT FROM AUTHOR]

Climate science depends upon accurate measurements of air temperature and humidity, the majority of which are still derived from sensors exposed within passively ventilated louvred Stevenson-type thermometer screens. It is well-documented that, under certain circumstances, air temperatures measured within such screens can differ significantly from "true" air temperatures measured by other methods, such as aspirated sensors. Passively ventilated screens depend upon wind motion to provide ventilation within the screen and thus airflow over the sensors contained therein. Consequently, instances of anomalous temperatures occur most often during light winds when airflow through the screen is weakest, particularly when in combination with strong or low-angle incident solar radiation. Adequate ventilation is essential for reliable and consistent measurements of both air temperature and humidity, yet very few systematic comparisons to quantify relationships between external wind speed and airflow within a thermometer screen have been made. This paper addresses that gap by summarizing the results of a 3-month field experiment in which airflow within a UK-standard Stevenson screen was measured using a sensitive sonic anemometer and comparisons made with simultaneous wind speed and direction records from the same site. The mean in-screen ventilation rate was found to be 0.2 m s -1 (median 0.18 m s -1), well below the 1 m s -1 minimum assumed in meteorological and design standard references, and only about 7 % of the scalar mean wind speed at 10 m. The implications of low in-screen ventilation on the uncertainty of air temperature and humidity measurements from Stevenson-type thermometer screens are discussed, particularly those due to the differing response times of dry- and wet-bulb temperature sensors and ambiguity in the value of the psychrometric coefficient. [ABSTRACT FROM AUTHOR]

Climate science depends upon accurate measurements of air temperature and humidity, the majority of which are still derived from sensors exposed within passively-ventilated louvred Stevenson-type thermometer screens. It is well-documented that, under certain circumstances, air temperatures measured within such screens can differ significantly from 'true' air temperatures measured by other methods, such as aspirated sensors. Passively-ventilated screens depend upon wind motion to provide ventilation within the screen, and thus airflow over the sensors contained therein. Consequently, instances of anomalous temperatures occur most often during light winds when airflow through the screen is weakest, particularly when in combination with strong or low-angle incident solar radiation. Adequate ventilation is essential for reliable and consistent measurements of both air temperature and humidity, yet very few systematic comparisons to quantify relationships between external wind speed and airflow within a thermometer screen have been made. This paper addresses that gap by summarising the results of a three month field experiment in which airflow within a UK-standard Stevenson screen was measured using a sensitive sonic anemometer, and comparisons made using simultaneous wind speed and direction records from the same site. The average in-screen ventilation rate was found to be 0.2 m s-1, well below the 1 m s-1 minimum assumed in meteorological and design standard references, and only about 7 % of the scalar mean wind speed at 10 m. The implications of low in-screen ventilation on the uncertainty of air temperature and humidity measurements from Stevenson-type thermometer screens are discussed, particularly those due to the differing response times of dry- and wet-bulb temperature sensors, and ambiguity in the value of the psychrometric coefficient. [ABSTRACT FROM AUTHOR]

Species introduced outside their natural range threaten global biodiversity and despite greater awareness of invasive species risks at ports and airports, control measures in place only concern anthropogenic routes of dispersal. Here, we use the Harlequin ladybird, Harmonia axyridis, an invasive species which first established in the UK from continental Europe in 2004, to test whether records from 2004 and 2005 were associated with atmospheric events. We used the atmospheric- chemistry transport model SILAM to model the movement of this species from known distributions in continental Europe and tested whether the predicted atmospheric events were associated with the frequency of ladybird records in the UK. We show that the distribution of this species in the early years of its arrival does not provide substantial evidence for a purely anthropogenic introduction and show instead that atmospheric events can better explain this arrival event. Our results suggest that air flows which may assist dispersal over the English Channel are relatively frequent; ranging from once a week from Belgium and the Netherlands to 1–2 times a week from France over our study period. Given the frequency of these events, we demonstrate that atmospheric-assisted dispersal is a viable route for flying species to cross natural barriers. [ABSTRACT FROM AUTHOR]

The continuous observations over a period of 7 years (2009–2016) available at 7 locations show declining trend of atmospheric BC in the UK. Among all the locations, the highest decrease of 8 ± 3 percent per year was observed at the Marylebone road in London. The detailed analysis performed at 21 locations during 2009–2011 shows that average annual mean atmospheric BC concentration were 0.45 ± 0.10, 1.47 ± 0.58, 1.34 ± 0.31, 1.83 ± 0.46 and 9.72 ± 0.78 μgm −3 at rural, suburban, urban background, urban centre and kerbside sites respectively. Around 1 μgm −3 of atmospheric BC could be attributed to urban emission, whereas traffic contributed up to 8 μg m −3 of atmospheric BC near busy roads. Seasonal pattern was also observed at all locations except rural and kerbside location, with maximum concentrations (1.2–4 μgm −3 ) in winter. Further, minimum concentrations (0.3–1.2 μgm −3 ) were observed in summer and similar concentrations in spring and fall. At suburban and urban background locations, similar diurnal pattern were observed with atmospheric BC concentration peaks (≈1.8 μg m −3 ) in the morning (around 9 a.m.) and evening (7–9 p.m.) rush hours, whereas minimum concentrations were during late night hours (peak at 5 a.m.) and the afternoon hours (peak at 2 p.m.). The urban centre values show a similar morning pattern (peak at 9 a.m.; concentration - 2.5 μgm −3 ) in relation to background locations but only a slight decrease in concentration in the afternoon which remained above 2 μgm −3 till midnight. It is concluded that the higher flow of traffic at urban centre locations results in higher atmospheric BC concentrations throughout the day. Comparison of weekday and weekend daily averaged atmospheric BC showed maximum concentrations on Friday, having minimum levels on Sunday. This study will help to refine the atmospheric BC emission inventories and provide data for air pollution and climate change models evaluation, which are used to formulate air pollution mitigation policies. [ABSTRACT FROM AUTHOR]

Abstract: Airflow through urban environments is one of the most important factors affecting human health, outdoor and indoor thermal comfort, air quality and the energy performance of buildings. This paper presents a study on the effects of wind induced airflows through urban built form using statistical analysis. The data employed in the analysis are from the year-long simultaneous field measurements conducted at the University of Reading campus in the United Kingdom. In this study, the association between typical architectural forms and the wind environment are investigated; such forms include: a street canyon, a semi-closure, a courtyard form and a relatively open space in a low-rise building complex. Measured data captures wind speed and wind direction at six representative locations and statistical analysis identifies key factors describing the effects of built form on the resulting airflows. Factor analysis of the measured data identified meteorological and architectural layout factors as key factors. The derivation of these factors and their variation with the studied built forms are presented in detail. [Copyright &y& Elsevier]

We investigate how well the variability of extreme daily precipitation events across the United Kingdom is represented in a set of regional climate models and the E-OBS gridded data set. Instead of simply evaluating the climatologies of extreme precipitation measures, we develop an approach to validate the representation of physical mechanisms controlling extreme precipitation variability. In part I of this study we applied a statistical model to investigate the influence of the synoptic scale atmospheric circulation on extreme precipitation using observational rain gauge data. More specifically, airflow strength, direction and vorticity are used as predictors for the parameters of the generalised extreme value (GEV) distribution of local precipitation extremes. Here we employ this statistical model for our validation study. In a first step, the statistical model is calibrated against a gridded precipitation data set provided by the UK Met Office. In a second step, the same statistical model is calibrated against 14 ERA40 driven 25 km resolution RCMs from the ENSEMBLES project and the E-OBS gridded data set. Validation indices describing relevant physical mechanisms are derived from the statistical models for observations and RCMs and are compared using pattern standard deviation, pattern correlation and centered pattern root mean squared error as validation measures. The results for the different RCMs and E-OBS are visualised using Taylor diagrams. We show that the RCMs adequately simulate moderately extreme precipitation and the influence of airflow strength and vorticity on precipitation extremes, but show deficits in representing the influence of airflow direction. Also very rare extremes are misrepresented, but this result is afflicted with a high uncertainty. E-OBS shows considerable biases, in particular in regions of sparse data. The proposed approach might be used to validate other physical relationships in regional as well as global climate models. [ABSTRACT FROM AUTHOR]

Indices have been used as indicators of synoptic-scale flow strength, shear vorticity, flow direction and static stability over Ireland and Britain. Changes in large-scale dynamic flow and static stability over the European region are expected because of shifting climate patterns, and investigation of how these indices change in future runs of global climate models allows us to estimate how this will affect storm frequency and intensity in the region. Analysis of frequency distributions shows an increase in westerly flows and decreases in most other flow directions, indicating an increase in rainfall for the region. The flow strength on days with strong winds increases in the future runs, as does the number of gale days. The future runs show not only an overall increase in atmospheric stability but also significantly larger areas with stronger instability during periods of extreme instability. Copyright © 2010 Royal Meteorological Society [ABSTRACT FROM AUTHOR]

We study the influence of synoptic scale atmospheric circulation on extreme daily precipitation across the United Kingdom, using observed time series from 689 rain gauges. To this end we employ a statistical model, that uses airflow strength, direction and vorticity as predictors for the generalised extreme value distribution of monthly precipitation maxima. The inferred relationships are connected with the dominant westerly flow, the orography, and the moisture supply from surrounding seas. We aggregated the results for individual rain gauges to regional scales to investigate the temporal variability of extreme precipitation. Airflow explains a significant fraction of the variability on subannual to decadal time scales. A large fraction of the especially heavy winter precipitation during the 1980s and 1990s in north Scotland can be attributed to a prevailing positive phase of the North Atlantic Oscillation. Our statistical model can be used for statistical downscaling and to validate regional climate model output. [ABSTRACT FROM AUTHOR]

• A dynamic, multi-zone model for heat pump demand profile simulation is presented. • The model is capable of rapid simulation at 5 s resolution. • The model is suited to batch simulation of multiple building profiles. • An interface that allows control logic modification is provided. • Results are consistent when compared to real data and equivalent EnergyPlus models. The electrification of heating is expected to grow in the UK domestic sector, and this has increased interest in the effects that this may have on low and high voltage network operation. However, Electrified heating profiles that alter with control decisions can only be obtained from dedicated building modelling that energy system modellers do not usually have the expertise to perform, yet these are required for meaningful studies. This work outlines a novel method for modelling air source and ground source heat pump power demand profiles using a multi-zone physics based building modelling framework with building fabric, thermohydraulic, and air flow subsystems. The novel setup framework allows detailed building layout, fabric and control properties to be assigned by analysts with no prior building modelling expertise. Once fully assigned, the building model can be used to generate heat pump power demand profiles at sub minute resolution. Upon testing, a single daily run of the model could be executed in 17 s. The model was then validated against real life test house data, under various control and weather conditions. A small relative error (typically within 10%) was observed between modelled and actual cycle lengths, and modelled and actual heat and electricity demands. Due to its rapid solution rate, the model is of significant value to energy efficiency and distribution network studies, where large demand profile sets that are sensitive to detailed retrofit and control considerations are often essential. The model has been made openly available. [ABSTRACT FROM AUTHOR]

A series of experiments was undertaken on an intercity train carriage aimed at providing a "proof of concept" for three methods in improving our understanding of airflow behaviour and the accompanied dispersion of exhaled droplets. The methods used included the following: measuring CO2 concentrations as a proxy for exhaled breath, measuring the concentrations of different size fractions of aerosol particles released from a nebuliser, and visualising the flow patterns at cross-sections of the carriage by using a fog machine and lasers. Each experiment succeeded in providing practical insights into the risk of airborne transmission. For example, it was shown that the carriage is not well mixed over its length, however, it is likely to be well mixed along its height and width. A discussion of the suitability of the fresh air supply rates on UK train carriages is also provided, drawing on the CO2 concentrations measured during these experiments. [ABSTRACT FROM AUTHOR]

A case study of aircraft measurements in the vicinity of a warm front over the North Sea is presented. Measurements of ozone, carbon monoxide and meteorological parameters were recorded at several altitudes behind a dissipating warm front by the U.K. Met. Office's C130 aircraft, operated by the Meteorological Research Flight on 3rd October 1997. The aim of the study was to investigate the composition of the warm conveyor belt (WCB), the main air flow associated with mid-latitude cyclones, which has the potential to transport boundary layer air containing ozone and its precursors into the free troposphere. Three distinct air masses were identified by changes in the parameters measured. Trajectory analyses together with synoptic charts showed that these air masses corresponded to a WCB and air ahead and behind it, and that the WCB consisted of marine air from the boundary layer and lower free-troposphere. The WCB was clearly identifiable as a distinct chemical air mass that retained its integrity even after the warm front began to dissipate; it contained lower ozone than the surrounding free tropospheric air due to its remote marine origin. [ABSTRACT FROM AUTHOR]

A hypolimnetic aerator operating in one of the City of Norfolk's water supply reservoirs was tested Dissolved oxygen (DO) profiles, water flow rate, and gas-phase holdup were measured over a wide range of applied air flow rates. A model that was developed to predict oxygen transfer in a Speece Cone was modified to conform to the conditions of the hypolimnetic aerator. By varying a single parameter (the initial bubble size) the model was found in provide a close fit to the experimental DO profiles as well as the observed gas-phase holdup. The mode was used to show that a doubling in oxygen transfer may be achieved if initial bubble size is reduced from 5 mm to 25 mm. Knowing the initial bubble size, it should be possible to predict water velocity by incorporating the effect of momentum. Further work is now underway to test this approach and to examine the possibility of extending this generalized model to cover the range of hypolimnetic aeration and oxygenation devices. [ABSTRACT FROM AUTHOR]

Buildings are responsible for 40% of the global energy usage to which infiltration-caused heat losses are responsible for 30%. Air infiltration is the unintended flow of air through leakage paths and fundamentally determined by the airtightness of a building. In the United Kingdom, building airtightness is conventionally measured through a blower door test and used to predict air infiltration in conjunction with the divided-by-20 rule, which is a rule of thumb that has been adopted by SAP (Standard Assessment Procedure: a UK government's recommended method system for measuring the energy rating of residential dwellings) for the estimation of the infiltration-caused heat losses for dwellings. This paper assesses the representativeness of this rule of thumb by carrying out blower door and tracer gas tests in twenty one dwellings located in the East Midlands Region of the United Kingdom. Results showed that a divide-by-37 rule would be more representative. It was also seen that the air infiltration rate is overestimated by SAP when modifying factors are added. The errors are as high as 500% in some cases. The most affected dwellings were the tighter ones. A revision of the usage of the divide-by-20 rule and the modifying factors is advised. • Introduction to the use of the divide-by-20 rule of thumb. • The rule showed to create differences as large as 175% with measured infiltration. • A more representative value for the leakage-infiltration ratio was shown to be 37. • When using the Standard Assessment Procedure, differences were greater than 500%. • The probability of predicting infiltration correctly is higher when using 37. [ABSTRACT FROM AUTHOR]

Indoor Air Quality (IAQ) in classrooms is assessed by CO 2 levels and Ventilation Rates (VRs). Factors affecting VRs fall into C ontextual, O ccupant and B uilding (COB) related factors. This study investigates how VRs are affected by COB factors in 29 naturally-ventilated classrooms in the UK during Non-Heating and Heating seasons. B uilding-related factors classify classrooms with high or low potentials for natural ventilation, with 45% of classrooms having high potentials. C ontextual factors including season, operative temperature (T op), outdoor temperature (T out), 'T op -T out ' and air density can limit or increase VRs. O ccupant-related factors classify occupant's good or poor practice of environmental adaptive behaviours. 'Open area' as a reflection of all COB factors is strongly correlated with ventilation rates. Results show that 12% and 19% of variations in ventilation rates are explained by open areas during non-heating and heating seasons, respectively. Findings highlight that to have VR of 8 ± 1.28 l/s.p during non-heating seasons and VR of 8 ± 1.07 l/s.p during heating seasons, average open areas of 3.8 m2 and 2 m2 are required, respectively. This difference can mostly be explained by temperature difference between inside and outside. Results show COB factors need to be considered holistically to maintain adequate VRs. Classrooms in which all COB factors are met provide average VR of 11 l/s.p and classrooms in which none of COB factors are met provide average VR is 3.1 l/s.p. This study highlights that 40% of classrooms according to EN 13779 and 80% of classrooms according to ASHRAE Standard fail to provide adequate VRs. • Same openings provide different airflow rates due to temperature difference. • Seasonal changes should be considered in openings' design to provide air quality. • When contextual, building and occupant factors are met, ventilation is 11 l/s.p. • 40% of classrooms according to EN 13779 fail to provide adequate ventilation rate. • 80% of classrooms according to ASHRAE fail to provide adequate Ventilation rates. [ABSTRACT FROM AUTHOR]

The article focuses on the issue regarding the noise complaint at the Department for Energy and Climate Change in Great Britain. It notes that the department has conducted an energy-saving trial by switching off air conditioning and use open windows for air. However, several employees have complained about the noise came from the construction works outside the department. The employees also complained about the high temperatures as well as security concerns and reduced air flows.

Synoptic-scale air flow variability over the United Kingdom is measured on a daily time scale by following previous work to define 3 indices: geostrophic flow strength, vorticity and direction. Comparing the observed distribution of air flow index values with those determined from a simulation with the Hadley Centre's global climate model (HadCM2) identifies some minor systematic biases in the model's synopticcirculation but demonstrates that the major features are well simulated. The relationship between temperature and precipitation from parts of the United Kingdom and these air flow indices (either singly or in pairs) is found to be very similar in both the observations and model output; indeed the simulated and observed precipitation relationships are found to be almost interchangeable in a quantitative sense. These encouraging results imply that some reliability can be assumed for single grid-box and regional output from this climate model; thisapplies only to those grid boxes evaluated here (which do not have high or complex orography), only to the portion of variability that iscontrolled by synoptic air flow variations, and only to those surface variables considered here (temperature and precipitation). [ABSTRACT FROM AUTHOR]