Advanced Design

The use of Computational Fluid Dynamic (CFD) modelling techniques allows advanced detailed analysis of building airflows and heat transfer, creating accurate predictions of actual building environmental performance.

Faber Maunsell has considerable experience in using CFD, which has been gained from providing CFD analysis/support to design teams on a variety of projects/applications.

CFD Capability

The ability to model both airflow and heat transfer allows many HVAC systems to be modelled. The ability to model the buoyancy effects of air/gravity allows stratification effects in displacement ventilation systems to be modelled, as well as stack driven flow in natural ventilation systems.

Convective and radiative heat transfer between surfaces can also be modelled, as well as solar radiation. This allows for comfort criteria to be determined using ISO 7730:1995 to look at Predicted Percentage of Dissatisfied (PPD), Predicted Mean Vote (PMV), cold down draughts and comfort temperatures.

As well as air, the software has the capability to model up to five other gases, which is useful in modelling cross contamination, indoor air quality looking at CO₂ levels or smoke control.

The modelling of wind and airflow in and around buildings can assist in determining the effectiveness of cross flow ventilation in natural ventilation applications. Wind pressures on facades can provide structural loading and turbulence effects.

In addition to the CFD software, Faber Maunsell have extensive experience in using computer simulation software. The APACHE Suite of programs models the dynamic thermal performance of buildings taking into account solar shading, thermal mass, operating profiles, different types of HVAC systems and their associated control strategies. The resulting boundary conditions from this model are used to feed reliable data into CFD analysis where it is required.

The software package used by Faber Maunsell is FLOVENT produced by Flomerics Limited, which is specifically designed for building services applications.

Thermal Modelling

Faber Maunsell is internationally recognised as an authority in the field of thermal modelling and simulation. Through the application of these techniques from the earliest point in the design process, through to detailed design, allows for the optimising of integrated building envelope and building services solutions in the context of Part L and Part J.

Through their highly specialised and technically advanced division, Faber Maunsell Applied Research, the company has been at the cutting edge of the development and application of energy modelling software for well over two decades.

As creators of APACHE Faber Maunsell are inevitably the best equipped to use the software and fine-tune the modelling/simulation process to the individual needs of the client. We not only support the work of the engineer, but also the architect and developers. Most thermal models are now constructed within the ModelIT program.

Within APACHE there are various modules that allow for links with the calculation of external shading effects from SunCAST and airflow analysis.

Fabric Analysis

Calculations such as thermal resistances, admittances, decrement factors and time lags are recorded for opaque constructions. Those conducted for glazed constructions include solar transmission, re-transmitted solar and various other solar attributes.

Building Heat Loss

Calculations for Building Heat Loss include steady-state winter heat loss, intermittent heat operation (particularly useful for boiler selection) and net annual heat requirement.

Building Heat Gain

Calculations carried out for Building Heat Gain are hourly room loads (with air conditioning systems in operation) and floating temperatures when the rooms are naturally ventilated.

System Simulation

System Simulation uses detailed weather tape information to produce detailed hourly room results, hourly psychometrics for air conditioning systems, monthly room and system loads, and monthly fuel consumptions at central plant.

VISTA is a results post processor that allows users to graphically look at any weather input data and room results on a daily, weekly, monthly or yearly basis. System simulation can also be used to provide a route to compliance with Part L of the Building Regulations and Part J in Scotland.

For more information on our experience and capabilities please contact Nick Barnard.