Natural Frequency is an electronic journal for articles on the environmental design of buildings and the application of analysis and simulation in architecture. You can browse articles by issue, author or topic using the links in the journal menu on the right.

Solar Availability in Cities

Dense urban environments provide a complex environment, where solar and daylight availability can become a scarce commodity, especially since buildings become increasingly taller. This is manly due to the complex dynamic overshadowing effects present on building surfaces. Accurately quantifying these effects is key in predicting reductions in solar availability. These in turn, can significantly affect daylight and thermal performance of buildings, as well as potential for PVs and other renewables. It is therefore necessary to use simulation tools to predict these complex effects.

Comparing Solar Position Data

I have had a couple of occasions recently where I needed to directly compare different solar position algorithms, as well as predicted versus recorded position data. This sounds pretty simple, but there are actually some interesting little quirks where even datasets that are so close as to be virtually identical will still throw up spuriously large differences in individual values. I thought these might be worth documenting and discussing.

ECOTECT and the Average Energy Year

When you perform solar and thermal calculations in Ecotect, it does not do these for any specific year, but rather a standard 'average' energy year. This is true of nearly all thermal and energy analysis tools. Even the weather files used for solar and energy analysis are usually averaged to better represent long-term conditions. This article explains the basic assumptions behind the 'average' energy year and why this approach is more appropriate than using any particular year.

Introducing Scripts in ECOTECT

Scripts have been available in ECOTECT from very early on in its development and are probably one of its most under-utilised features. Anyone can write and run a script in ECOTECT and they can be used to add new functionality, automate complex tasks, initialise or standardise a model to your firm's requirements, generate summary data, export to another application, etc. Pretty well anything you can imagine. This article is a brief description of what a script is and what it contains.

Are Highly Efficient Buildings Sustainable?

Many recent regulations and energy codes focus almost exclusively on energy efficiency during the operational life of a building. In our struggle to adapt to these changes and still appear 'modern', architects and designers are increasingly looking to energy-intensive materials and high-tech solutions, often ignoring many of the wider impacts of their projects. This article questions the true sustainability of these kinds of buildings and suggests that there are better ways to achieve the efficiencies we need.

Fitting a Spatial Analysis Grid

Many people have questioned why the analysis grid produced by the 'Auto-Fit Grid' function in Ecotect leaves a gap around the edges of a room rather than covering the full extents of its floor area. There is a very good reason for this and, as it touches on some more general analysis concepts, is deserving of some detailed explanation.

Averaging Solar Radiation

For the most part, the mathematics of solar radiation is pretty straightforward. However, there are a couple of situations that are less intuitive than they first appear. This is definitely true in the calculation of average hourly incident solar radiation (insolation).

Why Do Shading Calculations Take so Long?

Calculating detailed solar shading and overshadowing is a problem for most building analysis tools, ECOTECT included. It is important to a whole range of building performance criteria, from thermal and daylighting analysis through to solar access and rights-to-light. However, to do it properly can take a frustratingly long time. This article explains exactly what is happening during these calculations and offers tips on how to optimise the process and make best use of your existing shading data.

Solar Shading Potential

Not all parts of a solar shading device are equally effective or even necessary. Techniques have been developed in ECOTECT to visually map variations in effectiveness over the actual geometry of a modelled shading device. These same techniques can be used during the design process to map shading potential over a proposed device or even to determine the best location for shading. This article explains the concepts behind these techniques and how they may be best applied.

RADIANCE and Daylight Factors

The freely available RADIANCE software is one of only a few lighting analysis tools able to accurately calculate illuminance levels on surfaces within a building model. This article explains how illuminance levels can be used to generate daylight factors in RADIANCE and presents a number of ways of doing this, including using ECOTECT as a modelling interface. It also shows how both illuminance levels and daylight factors calculated in RADIANCE can be read back and displayed interactively within your ECOTECT model.

An Optimised Shading Example

A number of people have recently requested information on how to complete an overshadowing exercise I set some Masters students at a couple of different Universities. As a result, I have added some more descriptive text and reformatted the original answer sheet to describe both the exercise problem and an example method that can be used to generate the answer.

CAD Geometry vs Performance Analysis

With an increasing regulatory emphasis on energy efficiency and building performance analysis within the design process, the need for a smooth and hassle-free conversion from CAD tool to analysis engine is becoming critical. This article considers the issues associated with such a transition, looking in detail at the kind of information required by different performance analysis / simulation tools and what is actually available in a typical CAD drawing. It looks at the various options available, including the growing influence of Industry Foundation Classes (IFCs) and gbXML, and what their impacts might be.

The Thermal Effects of Solar Gain

In many building regulations and simplified analysis methods, solar effects on buildings are characterised only by the exposed apperture area and the average solar transmittance of the glazing used. However, the true impact of solar radiation on the internal conditions within a space are often much more complex than this simple relationship would suggest. To explain the problem, this article tracks solar radiation as it enters through a window and looks at the various factors that govern its resultant effects.

Making a Thermal Comparison

One of the first things many people say when introduced to analytical software is -- "OK, but just how accurate is it?". The accuracy of analysis software is important, but in the case of a thermal analysis tool this is not a simple question to answer. This article discusses the many issues you must first consider before comparing measured thermal values against simulation results, not just in ECOTECT but in any thermal analysis tool. It also makes a case for concentrating on relative accuracy in simulation rather than absolute accuracy.

Domes and Solar Radiation

Domed roofs have great structural advantages, but also some significant thermal advantages due to their response to incident solar radiation. This article presents a quick outline of this response when compared to flat or inclined roofs.

Thermal Modelling: The ECOTECT Way

For ECOTECT to properly understand a thermal analysis model, it requires that you adhere to some specific conventions when constructing it. A lot of work has been done to ensure that you can effectively model most building situations and that the same model can be both analysed in ECOTECT and properly exported to other tools such as EnergyPlus and ESP-r. This article outlines the important elements you must remember when creating thermal models and explains a few shortcuts you can take when modelling multi-storey, multi-zone and earth-bermed buildings.

Building Analysis: Work Smart, Not Hard

The most efficient approach when undertaking any form of work is to minimise your own effort whilst maximising the potential benefits and/or impacts that may flow from it. This should also be true of simulation and analysis work. This article discusses ways you can approach a project to achieve this, presenting a simple example to illustrate this idea in practice.

Office Acoustics

Open plan offices can be a difficult acoustic environment to design for. The ceiling is often the only surface you can use for any form of acoustic control. However, with the increasing use of exposed thermal mass, termodeck or chilled beams, even this surface is becoming off-limits. This article looks at some of the acoustic issues in open plan offices and considers how ceilings can accommodate these varies requirements.

ECOTECT as a Teaching Tool

With its highly visual approach to building analysis and simulation, ECOTECT has enormous scope to be used as a teaching resource at any level in both architecture and engineering courses. This article aims to provide some guidance on how to introduce ECOTECT to students. It discusses some of the main problems sometimes encountered and offers a series of suggestions for avoiding them. Whilst it concentrates on coursework integration, you should also check out some of the examples of its demonstration potential.

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