Ryan Southall

Test cell evaluation of supply air windows to characterise their optimum performance and its verification by the use of modelling techniques

Abstract A supply air window is a device that by using the space between inner and outer sashes as an air path enables ventilation air in winter to be pre-heated before it enters a room. For optimum results it is necessary to maximise the window’s capability as a heat reclaim device (by entraining into the air flow heat that would otherwise escape from the room) and its ability to absorb radiant energy from the sun. The principal requirements for achieving best performance include defining appropriate dimensional characteristics for the window, and the correct location of a low emissivity (low-E) coating within the glazing assembly. To determine these aspects tests were carried out using a PASSYS test cell. The performance of the window was monitored relative to climate conditions measured at an adjacent weather station. A simulation model of the test cell was built and comparison was made of the actual performance with forecast figures.

The VI-Suite: a set of environmental analysis tools with geospatial data applications

BackgroundThe VI-Suite is a free and open-source addon for the 3D content creation application Blender, developed primarily as a tool for the contextual and performative analysis of buildings. Its functionality has grown from simple, static lighting analysis to fully parametric lighting, shadowing, and building energy analyses. It adopts a flexible, mesh geometry based approach to the specification of calculation points and this has made it suitable for certain types of 3D geospatial analyses and data visualisation.ResultsAs this is the first academic paper to discuss the VI-Suite, a history of its development is presented along with a review of its capabilities of relevance to geospatial analysis. As the VI-Suite combines the functionality of 3D design software with performance simulation, some of the benefits of this combination are discussed including aspects that make it suitable for the processing and analysis of potentially large geospatial datasets. Example use cases with a 3D city model of the Hague are used to demonstrate some of the geospatial workflows possible and some of the result visualisation options.ConclusionsThe free and open-source nature of the VI-Suite, combined with the use of Blender mesh geometry to define calculation points, has encouraged usage scenarios not originally intended by the authors, for example large scale urban shadow and radiation analyses. The flexibility inherent in this mesh based approach enables the analysis of large geospatial datasets by giving the user refined control over the distribution of calculation points within the model. The integration of GIS analysis into a digital design package such as Blender offers advanced geometry/material editing and specification, provides tools such as ray casting and BVH tree generation to speed up the simulation of large datasets, and enhanced visualisation of GIS simulation data including animated city fly-throughs and high quality image production. The VI-Suite is part of a completely open-source tool chain and contributions from the community are welcome to further enhance its current geospatial data capabilities.

A programme of testing to evaluate a passive approach to whole‐house ventilation

Purpose – The purpose of this paper is to describe a programme of research into an innovative approach to whole‐house ventilation with heat reclaim. In order to save energy, houses are now required to be constructed to a high level of air tightness. This poses potential problems of indoor air quality, condensation and mould growth, with implications for human health. Adequate and controlled ventilation is a necessity, and in Europe the adoption of mechanical systems incorporating heat reclaim has become the preferred technology. The relatively mild climate of the UK undermines the efficiency of these fan‐driven solutions. The programme of research has been to test the viability of an engineered system of natural ventilation for use in temperate regions.Design/methodology/approach – The system works by the combination of “supply air” windows and passive stacks. The windows have an air path for incoming ventilation that passes between panes of glass, the pressure drop across the windows to induce the air fl...

Comparison of the Performance of a Whole House Low Energy Ventilation System in Contrasting European Climatic Regions

An experimental ‘whole house low energy ventilation system’ has been installed and tested in dwellings in Denmark and Poland. Both sites have adjacent houses of identical plan layout, which have been used as a control for the experimental dwellings. A weather station was installed adjacent to each site, and each of the dwellings, test and control, has been extensively monitored to measure indoor airflow and comfort conditions, and the amount of energy being supplied for heating in winter. The design of the systems was established by computer fluid dynamic (CFD) analysis and by a dynamic simulation using ESP-r. The low U-values that can be achieved by ‘air supply’ windows, suggested by previous tests and simulations, have been confirmed by the monitored results. Similarly the levels of preheat to ventilation air achieved by the windows have reached the percentages expected from the simulation models. Practical application: This study is part of an ongoing investigation into the use of an innovative technology for whole house ventilation. Since this is the direction of the forthcoming revision to the UK Building Regulations it has obvious implications for practice.

Derivation of a Theoretical Model to Explain the Functioning of a Window as a Pre-Heat Ventilation Device and its Verification using Physical Models

Abstract ‘Supply air’ windows are designed with an air gap between the inner panes of glass that is used as the incoming air path for room ventilation; air is pre-warmed within the window and thereby avoids the sensation of draughts. A series of tests, verified by model simulations, were carried out to determine those aspects of the window’s specification that govern the extent to which air is pre-warmed by the windows before entering rooms. The first was a laboratory experiment investigating the influence that the width of gap between the glass panes had on the pre-heating of the airflow, the results from which were simulated using an algebraic model based on fluid dynamics principles. The following experiments were carried out in test cells analysing the influence of the location of a low emissivity coating within alternative glazing assemblies, the relationship between pre-heat temperature and ambient temperature, and its variation with ventilation rate. The later stages were modelled by the use of the Computational Fluid Dynamics program FLOvent. The outputs of these experiments and simulations has enabled a clearer understanding of the physical processes at work, and the development of simulations that accurately predict the window’s performance as a pre-heat device.

Description of a Programme of Testing and Simulation to Establish the Determinants of the Effective U-Value of a "Supply Air" Window

The ‘supply air’ window is in essence a modified Scandinavian ‘double’ window having outer and inner sashes with a gap between them forming a route for the ingress of ventilation air. When operating under optimum flow conditions, the air stream is laminar, so that a high proportion of the heat escaping from the room is entrained in the air path and returned to the room as pre-heated ventilation air. In this way very low U-values can be achieved and a proportion of the ventilation heat load is met by the preheating of the incoming air. A series of tests have been carried out using a laboratory test rig and test cells to determine the optimum specification for the window and its glazing in order to achieve the best performance in terms of insulation, indoor air quality and comfort. The results presented here investigate the factors influencing the U-values that can be achieved. The data from experiments has been compared with model simulations preparatory to testing under real house conditions.