The IES <Virtual Environment>

Transcription

1 The IES <Virtual Environment> By Don McLean, IES Limited Organisations throughout the AEC industry are looking for increased productivity and to produce better buildings. To help the industry achieve these objectives IES has recently launched Version 4 of the <Virtual Environment>. The <Virtual Environment> is a unique suite of software products capable of simulating a building and has been proven to improve the design process resulting in better and more cost effective buildings. Using the <Virtual Environment> is equivalent to building a physical model of the building within the computer and testing how the building will operate. This system extends the concept of Virtual Reality for building designers, instead of only visualising the 3D space the designer can compare and contrast how the building will perform in terms of daylight and electric light, occupant comfort, energy usage, sustainability, health and safety and capital and running costs. With the <Virtual Environment> design teams have a much greater insight into how the building will actually perform after it has been built by answering many of the 'what if' questions. The <Virtual Environment> can be used at any stage in the design process or post-occupancy. The system is particularly useful pre-cad where many design decisions are taken that can have significant bearing in the overall cost and performance of the building. The technology underpinning the IES <Virtual Environment> has been developed over many years of research and through application to commercial projects. The <Virtual Environment> product range has a proven track record in: Substantially reducing building capital costs Significantly reducing running costs Reducing costs by speeding up the design process to get the design 'right first time' Minimising energy consumption, thereby reducing atmospheric pollution and improving our external environment Rectifying or reducing the risk of "Sick Buildings" It is widely accepted throughout the AEC industry that greater use must be made of building analysis applications to improve the quality of the final product. The <Virtual Environment> is unique in meeting many of the requirements defined by Egan in his report entitled 'Rethinking Construction'. It allows the design team to 'test drive' buildings, helping reduce the risks and costs associated with a project enabling the project team to adopt a 'right first time' approach. Answering 'What if' Questions Most of the currently used computer software in the construction industry is aimed at assisting the 'Production' of buildings. For example 2D drafting tools and 3D modelling systems are primarily aimed at assisting the design process in terms of generating working drawings. With a 3D modelling approach the principal CAD vendors rightly expound its virtues by offering improved co-ordination between disciplines, helping visualise design intent and more easily generate design information such as bill of quantities, using the data model throughout the building lifecycle. Whilst it is extremely important to increase design efficiency how do building professionals address the 'What if' and performance issues in their designs? For example will glare be a problem? Can natural ventilation be used? How can people be evacuated safely in the event of a fire? Will people be comfortable? To answer questions such as these requires an alternative approach because in many instances, due to the poor quality of relevant performance information, designers must rely on their intuition when making design decisions. In order to design a better product, building simulation tools are required to provide a fuller understanding and insight of the design problems. Although building performance based tools have been available for many years and their benefits clearly demonstrated they have not yet become part of the design process because of difficulties in implementing building analysis technology throughout an organisation and as a result there has been a poor uptake of such technologies in the AEC industry. Integrated Environmental Solutions Ltd. (IES) has been developing the <Virtual Environment> over many years in order to overcome the problems these 'implementation' problems. The principal features of Version 4 include: Figure 1-<Virtual Environment> A single data model approach to eliminate repetition and reduce the risk of errors from data inconsistency across the various applications. Allowing design information to be reused from other projects including various databases to store organisations proprietary design information. Improved inter-disciplinary communication as the design team have a much better means of communicating design intent to each other and the client. A wide range of easy to use design tools that can be deployed throughout the organisation. Three levels of interoperability: Model (using the IDM as much as possible); Application (where information from one product is used to improve the analysis of another product); Third-Party (connections to third party products include CAD and Microsoft). P34, VOL 2, ISSUE 6 EXCITECH COMPUTERS LIMITED 2002 DESIGN PRODUCTIVITY JOURNAL

2 The commercial benefits (marketing differentiation, technical differentiation and now productivity) of Version 4 of the <Virtual Environment> has been demonstrated. Consequently, many of the leading UK companies have already bought into the latest version of the <Virtual Environment>. These include White Young Green, Hoare Lea, Ove Arup, Oscar Faber, WS Atkins, DSSR, Silcock Dawson and Partners, Troup Bywater and Anders, Barrett Lloyd Davis Associates and Abbey Holford Rowe. The <Virtual Environment> The <Virtual Environment> consists of several groups of products. The ability to quickly create a single Integrated Data Model (IDM) that is used by the IES building analysis applications is fundamental to the system. This IDM is managed by the products in the ModelBuilder group allowing the user to create and manage a model of the building, with or without CAD data. Hence the basic building form can be: Entered directly into ModelIT Converted from an Architectural Desktop 3D model Converted from a CAD 2D drawing from 'AutoCAD', MicroStation' or in 'DXF' format These products meet the needs of a number of users. For example: Architects: IDEAL, CostPlan, LifeCycle, Simulex, SunCast and Radiance. Mechanical Engineers: APACHE-calc, Pisces, TAPS, INDUS and VE-Ductwork Electrical Engineers: FLUCS, FIELD16 and LISI Consultants: IDEAL, CostPlan, LifeCycle, APACHE, MicroFlo, SunCast and MacroFlo These products make as much use of the IDM as possible (Model Interoperability) plus there is strong Application Interoperability. The links to CAD and to Microsoft Office for reporting demonstrate 'Third Party' Interoperability. No other company in the world can offer such a suite of interoperable products. Example Projects To illustrate the benefits of the <Virtual Environment> several users have provided example projects where they have successfully applied the technology. 1. WS Atkins The selection of projects included details WS Atkins in house experience to date, currently five mechanical engineers and four electrical engineers in Epsom have been trained in the use of the IES <Virtual Environment> software. The extensive experience of IES can be relied upon for support in carrying out larger, more complex projects. 2. Exeter Crown Courts As part of this new build PFI project court room and associated office areas were modelled and simulated to determine whether the proposed four stage ventilation strategy would succeed in maintaining comfortable conditions of temperature. For BAFO it was possible to demonstrate the extent of overheating and how to resolve it, effectiveness of natural and displacement ventilation systems and the need for external shading on south facing offices using the thermal simulation, bulk air flow modelling and Suncast modules. Archit chitec ectur tural Figure 2-The <Virtual Environment> The prime data sets that are used by most of the <Virtual Environment> applications are held in 'Building Templates' and can be applied quickly and easily to the geometry as it is created. These 'Templates' can hold customer specific or your proprietary information to give your company a competitive edge. In addition, a single model can significantly improve work flow between the various members of a design team and, for Partnerships familiar with the single model approach, the Client can be offered a more coherent and efficient service. There are a number of product groups that have one or more products that address particular aspects of building analysis e.g. Thermal, Solar, Lighting and Cost. The individual products in each product group are summarised below. The <Virtual Environment> Building Analysis Products Having created the IES Integrated Data Model several suites of building analysis products are available with the <Virtual Environment> System. Figure 3-Exeter Crown Court 3. Cambridge Medical Research Council Institute of Public Health This project consisted of modelling and simulation of an existing office block where there had been complaints from staff of unacceptably high temperatures in summer. With the software we were able to identify the extent of the overheating and demonstrate the cause. We also demonstrated effects of a range of possible solutions, and were able to show that rather than opting to install cooling straightaway, as the building owners were under pressure to do from the users, a mixed mode strategy could be considered instead EXCITECH COMPUTERS LIMITED 2002 DESIGN PRODUCTIVITY JOURNAL VOL 2, ISSUE 6, P35

3 6. Rhondda Cynon Taff Using Radiance it was possible to model the effects of using Monodraught suncatchers on classroom roofs in terms of enhancing daylight levels to the rear of the rooms. Figure 4-Cambridge Medical Centre 4. Woodwater Park A complete appraisal of four different comfort cooling systems was carried out for this generic office building. Fan Coil Units, Variable Air Volume, Displacement Ventilation and Chilled Beams and Termodeck were modelled in detail using Apache HVAC, linked to a generic office building model and simulated. An in depth appraisal was carried out looking at capital, maintenance and running costs, future flexibility, spatial implications, comfort and controllability. Figure 7-Rhodda Cyon Taff-3D Classroom image (looking from window wall to rear of class) without Monodraught suncatcher. Figure 8-Rhodda Cyon Taff-Same view of room showing lighting evels achievable with Monodraught Suncatcher. Figure 5-Woodwater Park 5. Swiss Cottage The proposed climbing wall extension to this sports hall in North London was to be naturally ventilated. Suncast was used to analyse the largely glazed South West facade in detail. Results of the analysis were used to design external shading, which in turn reduced solar gains to a level whereby natural ventilation could be used to maintain acceptable internal conditions. Macroflo was also used to examine whether the Monodraught units could be used to enhance cross ventilation and whether these in conjunction with openable windows would provide sufficient free cooling to avoid the need for air-conditioning. Figure 9-Rhodda Cyon Taff Figure 6-Swiss Cottage 7. BLDA BLDA Consultancy carries out sunlight, daylight and rights of light evaluations on large proposed commercial developments in London and other major conurbations. P36, VOL 2, ISSUE 6 EXCITECH COMPUTERS LIMITED 2002 DESIGN PRODUCTIVITY JOURNAL

4 The sunlight and daylight assessments are in support of applications for planning consent. Rights of light assessments are carried out to advise on possible infringements of such rights, which can arise either by agreement or by prescription after 20 years. We use IES software to model developments under evaluation. We have worked with IES products for some six years, upgrading to the latest version about six months ago. Our work requires us to assess light reaching both the proposed new building and existing buildings which may be affected by new development. We construct models in ModelIT Version 4 either from CAD files supplied by the design architect or, for surrounding buildings, from digital survey data. The resulting 3D digital model can then be assessed using Radiance (for daylight) and SunCast (for sunlight analysis). For our rights of light assessments we construct models so that the 0.2% sky factor contour can be plotted at 850mm above floor level. Based upon accepted parameters we are able to provide accurate assessments of light. Daylight levels have historically been difficult to assess. Are the assessments of a bright day or an overcast day? How much light is reflected externally? What about light reflected internally? To overcome these difficulties "sets of rules" have been adopted, both for Town Planning Daylight assessments and for rights of light matters. In rights of light matters, for example, reflected light is not taken into account. With the increase of computing power, and advances in software, it is now possible to make more realistic light level assessments constrained more by reality than rule. We are investigating how such "realistic" assessments might become more useful in the formal work we undertake. There are many policy pressures to increase development densities in appropriate locations. With the use of significantly greater computing power we are seeking more accurate light prediction and more realistic "benchmarks" and ways of assessing these. Our aim is for realistic light level projections. The illustrations show examples of recent outputs in the work undertaken by BLDA Consultancy. Figure 10-Example of existing building model for internal assessment Figure 11-Typical Room Output Assessment 8. Troup Bywaters & Anders Troup Bywaters and Anders have implemented the IES Virtual Environment software company-wide as their main tool for the analysis of the overall thermal performance of the building envelope and for the sizing of building services plant to control the internal environment. Increasingly, TB+A is able to 'add value' to a project by providing advice to the design team at a early stage as to how the overall building envelope can operate as a 'climate modifier', working together with the building services systems to provide and maintain a good internal environment. The IES Virtual Environment software is a key tool for such analysis work. A typical such application for the software was in a study of the impact of a variety of façade solutions on the overall heat gain to a new 8000m2 speculative office development in South London, The client's specific requirement was that the building achieved the 'very good' BREEAM (Building Research Establishment Environmental Assessment Method) rating and achieve the 'good practice' target of the DETR's 'Energy Use In Offices' Energy Consumption Guide 19 (ECON19) The architect had already established that the building form would incorporate external façade containing high proportion of glazing for good day lighting, combined with a means of controlling direct solar heat gains within the building to an acceptable level. The solar shading device incorporated in the façade would reduce the cooling energy required, and thus contribute to the overall energy efficiency of the development. To this end, the building was initially modeled in ModelIT with a typical office glazing solution (double-glazed windows with internal fabric roller blinds). SunCast and ApacheCalc were then used to establish a base cooling load for the building. It was then straightforward to modify the model for four different shading options (external blinds, solar performing glass, mid pane blinds and internal timber blinds ) and make comparisons between each option and the base cooling load. The aim of the design team was to identify the optimum means of reducing the overall cooling capacity of the building whilst minimising the visual effect of the external facade. In turn in was possible for the project team to price the options and then make a comparison between the higher capital costs of the enhanced shading systems and the savings to be made in ongoing energy costs. In this case it was demonstrated that external fixed louvers offered the best solution. One of the interesting results from ApacheCalc was the comparison of the impact on the overall cooling load of internal timber blinds against the more traditional light coloured venetian blinds. It was demonstrated to the design team that ( counter-intuitively ) internal blinds did not reduce the heat gain to the building, and that from a heat gain perspective it was better not to use wooden internal blinds at all. The ease with which different options could be integrated into the model meant that it was easy for the design team to try out a wide variety of systems and assess their environmental and cost impacts in a relatively short period of time. It is unlikely that without the use of such software, such a series of studies could have been carried within the design period allowed. 9. Hoare Lea Virtual Engineering: Solar Shading. Hoare Lea Virtual Engineering ( are a specialist group within Hoare Lea Consulting Engineers that provide detailed simulation, visualisation and software development services for external clients and well as a dedicated service within Hoare Lea. Solar shading is an essential part of the dynamic modelling process. There are two distinct elements of any solar shading analysis. Firstly, and of primary importance to the majority of dynamic thermal simulations, is to establish the level of incident solar gain into the simulated space, and then to establish the effect of any system utilised to reduce solar gain. Archit chitec ectur tural EXCITECH COMPUTERS LIMITED 2002 DESIGN PRODUCTIVITY JOURNAL VOL 2, ISSUE 6, P37

5 Secondly, solar shading analysis can be used to aid visualisation of the proposed building throughout the year, and identify the effect of the location of the building with respect to it's surroundings. This approach can assist with the orientation of key features in a building or indicate any potential problems with 'right to light'. Three projects where both elements of solar shading analysis were investigated by Hoare Lea Virtual Engineering, using the IES SunCast product, are: Evelina Children's Hospital London, a proposed new multi-use development in Liverpool city centre, and in the centre of Bristol. Detailed solar shading analysis was requested by the design team to identify on all the façades where beneficial solar shading from these surrounding buildings occurred. This analysis would then identify all the locations where further solar protective measures would be required. A full year visualisation analysis was performed; detailed interrogation of each façade identified the amount of beneficial shading. By performing this type of analysis the level of solar protective measures can be optimised, improving thermal performance within the space and lowering the build cost of the project. Figure 12-Evilina Childrens hospital The proposed Evelina Children's Hospital, (Figure 5), has a four storey curved atrium structure along the whole of it's south façade. This atrium is to be used as a circulation space and to form a thermal buffer between the ward areas in the hospital and the external conditions. It was the intention of the whole of the design team, that due to the large volume of the atrium, the whole space should not be conditioned, and that wherever possible, passive measures should be used to minimise solar gains into the atrium. Solar shading analysis was performed on the atrium to establish the peak summertime temperatures and also to visualize the path of the sun to assist with the location of any solar protective measure. A pre-defined set of desirable internal conditions throughout the simulated year within atrium and in the adjacent ward areas were used as performance indicators. Through close liaison with the design team an extensive set of trials were identified and carried out on this building to identify the optimum solar gain reduction performance of different combinations of glazing type and different configurations of brise soleil. Figure 13-Proposed Development Liverpool City Centre The new development in Liverpool, (Figure 6), was a solar shading analysis project where the impact of the surrounding buildings was of primary importance. This project required the aid of the visualisation aspect of solar shading analysis. The proposed development is located in the centre of Liverpool surrounded closely by tall buildings. Figure 14-Proposed Development, Bristol The proposed development in Bristol is a large mixed-use development project. The client requested that passive solar protective measures should be considered to reduce the likelihood of summertime overheating. Each facet of the development had different internal design conditions that needed to be met, wherever possible, with limited use of mechanical systems. Further to this, due to the size and extent of the project, the impact of overshadowing of the surrounding buildings was requested. This project therefore required both aspects of solar shading analysis, visualisation and thermal performance. In close liaison with the design team and client a number of trials using solar protective measures was agreed, plus a full year visualisation to establish the extent of the overshadowing. The solar protective measures included a number of glazing options, overhangs, balconies, projections and brise soleil. After performing the thermal performance tests for a three-month summer period a series of recommendations were proposed identifying the relative performance of each of the solar protective measures. Summary In order to make improvements in our built environment we need to use a holistic approach to building design. The IES <Virtual Environment> system will help provide the clients design brief and then support the design team from the initial sketch design phase, through to detailed design and construction. The Integrated Data Model (IDM) and the application software can then become part of the control system and form part of the Facilities Management system. The IDM will be active throughout the building life cycle and it will consist of different layers of design data attributed to the building CAD geometry. Building simulation technology is being used on an increasing number of projects. These simulation tools have proven to not only enhance the design process but also result in significant capital and running cost savings. This results in better buildings at a lower cost with a reduced risk of poor building performance and is equally applicable to refurbishment projects as it is to new build. In the longer term, the use of simulation technology will result in a shift in emphasis in the design process. The design process will be no longer centred on CAD, as more effort will be taken at the early stages of the design process allowing design teams to make more effective design decisions. MORE INFO 2609 see page 74 or call Excitech on P38, VOL 2, ISSUE 6 EXCITECH COMPUTERS LIMITED 2002 DESIGN PRODUCTIVITY JOURNAL