Controls on the Vertical Profile of Moistening as a Function of Precipitation Rate

The relationship between moisture tendency and precipitation rate has been identified as a process diagnostic relevant for simulation of the MJO. AGCMs with moistening that progressively deepens with precipitation rate demonstrate greater MJO skill (Klingamanet al., 2015). However, the processes that give rise to this net moistening pattern are poorly understood. Here we use the NASA Global Earth Observing System (GEOS) AGCM to examine the moisture budget in precipitation-space and understand its sensitivity to changes in model parameters. Comparison is made with the MERRA-2 and ERA-5 reanalysesto place model results in context

Evaluation of GEOS Total Cloud Fraction with GLOBE Citizen Science Observations and Co-Located Satellite Data

Here we evaluate the total cloud fraction in cycled forecast experiments with the NASA Global Earth Observing System (GEOS) model. Forecasts were run for summer and winter periods of 2017/2018 and compared with ground-based and satellite observations. Citizen science observations from the Global Learning and Observations to Benefit the Environment (GLOBE) Program were matched with MODIS satellite overpasses and geostationary cloud fraction, yielding a dataset of coincident observations for comparison with hourly model output. The observations indicate a model bias toward overcast and clear conditions, with underestimation of intermediate cloud fractions. We investigate underestimation of variance in the sub-grid total water probability density function (PDF) as a possible cause. The PDF determines large-scale cloud fraction as the sub-grid fraction with total water exceeding the saturation specific humidity. We conduct model experiments in which the shape, width, and spatial dependence of the PDF are varied, and consider the impacts on cloud fraction relative to the combined observations

Results of Belgian quality control framework for cavity wall insulation

A

Design principles for pressure moderated window frames

High performance window frames that are widely used in Europe rely on pressure moderation to achieve a good weathertightness. By separating the airtightness plane from the water shedding surface a drained cavity can be pressure moderated. As wind pressure is the main driving force for water to infiltrate into the frame, a pressure equalized system is able to achieve higher performance levels. In this paper the performance of window frames is analyzed in two separate ways: first of all experimental research was conducted on a single frame to analyze the way it functions and fails, secondly a database of the university window testing facility was used to perform a parametric analysis. High frequency measurements on window frames provide for the information to model the pressure in the cavity and render information on prevalent parameters. The influence of different elements (section, joggles, gaskets, fittings) is examined in both dry as well as rainy conditions during static and dynamic pressure differences. The airtightness of the outer plane divided by the airtightness of the inner plane is the main parameter that will determine the watertightness potential of window frames. Based on the research carried out within the framework of that program and the analysis of the test reports in the database design principles have been determined requisite to achieve adequate pressure moderation in window frames

Pushing architectural quality further

In this paper, the intentions thriving the implementation of computational modeling of building physics as it is approached in the Architectural engineering courses at Ghent University are discussed. During the bachelor degree, courses focus mainly on integration of basic building physics feasibility in the architectural conceptualization. During the final bachelor year, students program their own simplified 2D models for internal condensation and thermal bridges in a spreadsheet, based on realistic detailing from buildings they studied in other courses. These models are intentionally kept both simplified and strongly mathematically based to nurture thorough comprehension of the physical background of problematic design options. Additionally, evaluation of energy performance with official EPB-software is incorporated in the courses because of its high relevance as a legal benchmark. All these models, including EPB, are (semi)static and thus offer only limited but nevertheless useful information on physical, legal, hygienic… viability of different options at reasonable complexity. Furthermore, they induce basic modeling skills as a basis for further development. During the master’s degree, the focus shifts from taxation of the feasibility of design decisions towards energetic performance as one of the starting points and validation criteria of the design process. For students who wish to specialize in the matter, elective courses and master’s thesis projects on optimization, innovative techniques, passive building standards etc. are offered in which advanced dynamic modeling is used. These models offer an important input for this specific design process as they enable precise, nuanced validation of the robustness and sensitivity for certain parameters of different strategies in a given, very complex, situation. By developing both innovative, more precise models for the master classes besides more powerful integration of modeling with design software (BIM) and robust predesign templates for the bachelor courses with master’s student cooperation, the research team supports these courses in achieving output of the highest possible quality

Watertightness of window frames: experience of notified bodies

The research facility for testing building envelope elements at Ghent University has been testing the air- and watertightness of windows for over 30 years. As a certified lab a lot of tests are done for the industry according to standard procedures. This paper presents the results and analysis of about 200 tests that were carried out throughout the last 10 years. Is the overall performance of the window correlated with the construction material? And does a good airtightness guarantee a corresponding watertightness? All too often the test samples delivered by the industry are an exception to the rule: while a grade A window is delivered to the lab, poor quality is general practice. Clients, architects and contractors need clear-cut specifications concerning performance assessment in order to obtain a high-quality product, and if there are apparent indications of defects or flaws the specifications should provide the possibility to put a randomly chosen window to the test. Based on the experience of the test lab as notified body guidelines for quality management in low-rise and high-rise buildings are developed

Preliminary Evaluation of the Simplified Higher Order Closure (SHOC) in the NASA Goddard Earth Observing System (GEOS)

Here we evaluate alternative planetary boundary layer (PBL) schemes in the NASA Goddard Earth Observing System (GEOS) model. The model currently calculates turbulent diffusivities with a local Richardson number-based scheme for stable layers, and a K-profile scheme with surface- and cloud-driven plumes based on Lock et al. (2000) for unstable layers. In this study, these are replaced with the TKE-based Simplified Higher Order Closure (SHOC). SHOC combines a 1.5-order turbulence closure with a double-Gaussian PDF serving as a subgrid condensation scheme. The new diffusivity calculations are paired with two new shallow mass flux schemes. First, the University of Washington shallow cumulus scheme of Park and Bretherton (2009), a buoyancy-sorting entraining-detraining bulk plume with overshooting entrainment and a TKE/CIN-based closure. Second, an Eddy Diffusivity Mass Flux (EDMF) scheme based on the multiple plume model of Suselj et al. (2013) with stochastic lateral entrainment. Global climatologies of low level temperature, humidity, and wind are evaluated against MERRA-2 and ERA-Interim reanalyses, and significant reductions in bias are seen with both mass flux schemes. The diurnal cycle over the continental United States is evaluated using MERRA-2 and an in situ network of surface Lidar profilers

HOUSEHOLD BIOSAND WATER FILTERS: MATERIALS, CAPACITY, AND TEMPERATURE EFFECTS ON PERFORMANCE

The household biosand filter (BSF) is one of the world’s most utilized point-of-use (POU) water treatment tools where drinking water is not reliably potable. The feasibility of using ferrocement for construction, the filter volume, and the effect of temperature on removal are unclear, however. The following field and laboratory research was carried out in Panama and at Michigan Technological University. Field testing of ferrocement biosand filters (FBSFs) in rural Panama yielded average coliform and E.coli removals that compared favorably to plastic and cement BSFs. Parallel testing of a larger-bodied FBSF and a conventionally-sized BSF revealed that the former is necessary to sufficiently purify dose volumes greater than the recommended 12 liter influent. Additionally, for optimal treatment, no more than approximately three-quarters of the total pore volume should be introduced per day. Model filters in different temperature labs showed that while immediate filter performance varies by temperature, over time, BSF performance adjusts to be similar for all tested temperature values. Finally, exposure to extremely reduced temperatures and freezing severely reduced filter performance compared to control filters

Airtightness assessment of single family houses in Belgium

Airtight construction lies at the heart of achieving high energy performance in dwellings. But how well does it apply in new construction? This paper presents results from airtightness measurements on 44 randomly selected, standard new built single family houses in Belgium and from 4 case studies including 78 additional measurements. The houses were randomly selected after completion, to assure that standard workmanship was used during construction. Where applicable, the effect of incorporating the attic and garage in the building volume was measured by performing a series of tests in different configurations. The results are compared with those from a previous study in the early 1990's, with a database that was compiled with results from 161 air tightness reports executed on newly built dwellings by private party consultants and with the governmental EPBD-database (1884 measurements). The results show that the mean leakage rate is about 6 ACH(50) for the randomly selected houses and 3 ACH(50) for the houses in the databases. The houses in the databases are measured upon the initiative of the owner. Therefore, the attention to airtight workmanship is substantially higher for these cases than in the randomly selected houses. This clearly demonstrates the difference between 'mainstream' workmanship and results obtained by the 'engaged' market