Hello All - I've been following this thread with interest for a week or so but have only now found the time (new baby and part-time MSc currently occupying my spare time) to get involved.
A few comments:
Having recently completed the 'Computer Applications' unit on the UEL CAT Msc course, which introduced us to dynamic simulation in building design using IES, it's encouraging to see many of the same issues being discussed here. Amongst other things, I can say that Eric Roberts comments on the 23rd of April were echoed by the course tutors throughout the week. Several MSc student have previously prepared essays on the weather data issue as well and I am aware of a study done by ARUP and ZedFactory that looked at the potential effects of climate change on buildings.
Using IES (ApacheSim) I am currently modelling the effects of different levels of airtightness on the AECB Silver Standard dwelling as described in the most recently published information: 80m2, , semi-d, passive solar design with overheating proectction etc. One of my initial aims, in the absence of empirical, 'live' data, is to effectively calibrate the model to yield more realisitc results. I would like to be able to gain a clearer understanding of how important airtightness is in approximate kWh/m2/yr terms - as given in the AECB Standards.
After many unsusccessful attempts and entering my own user profiles (what a chew!) for heating, casual gains, ventilation etc, I have used the standard NCM profiles supplied. Rather suprisingly I managed to achieve results for the dwelling's heating in kWh/m2/yr (62) very close to the 58 predicted by the AECB. I have also managed to achieve a similar 'success' (my 'real U-value' results - 146 / AECB's 'real U-value' results - 147 ) with a building regs compliant (non-passive solar design but same as previous model in every respect).
I've not yet managed to achieve the AECB Gold levels of performance with the model, mainly because setting up a heat recovery profile, which is critical, would take more time than I have to invest at the moment and its not on the 'critical path'.
I realise the shortcomings of SAP (and presumably SBEM) in terms of what they leave out - cooking, lighting and what they don't properly account for - thermal mass. Would NCM based profiles suffer the same affliction? Given that my main interest in the modelling above is the heating energy, it's not critical for the exercise, but I would like to know more about the NCM as the IES and BRE information on it so far seems thin on background explanation or even 'foreground' explanation - i.e. what it includes!
I have two questions:
(David O.?) Was the research conducted to estblish the AECB standards based in some part on NCM data?
If not, is it valid to use it to calibrate in the model in the exercise described above?
One final note - In addition to stressing the importance of simulation validation (with measured data where possible), one of the main topics of discussion during the week was understanding the purpose and usefulness of buildng simulation not so much in terms of absolute values (this design will produce x kg/CO2/m2/yr) but more in relative terms (design A is a % improvement on design B).
Any input or comments welcome.