Ideas wanted to pass Part O Simplified modelling or to use Dynamic modelling?

[Susie]

Having got our planning permission in October our architect is only just looking at drawing the building regulations up, and looking at Part O.  He wants another company to do the modelling, simplified and dynamic. 

 

By my own calculations, we haven’t passed the simplified model, and I have had to change almost every fixed window to an opening window.  The cost of this change could lead into thousands of pounds, and a possible increase in the sight lines.  Since we already have planning permission I don’t really want to start changing windows too much.

 

I think the Dynamic thermal modelling method will take into account MVHR, which we have already planned to include in the build.   Does anybody know if dynamic modelling can take MVHR into consideration and keep most of my fixed windows.  I don’t know how much the dynamic modelling would cost but would hopefully not be as much as changing all my fixed windows to opening windows.

 

We are also a bungalow with downstair bedrooms, with 2 windows open 30⁰ and one 15⁰ at night.  We are in a very safe area and I don’t see this as a problem especially as in reality they would be on vent with the MVHR on but I do have to take security into consideration for the simplified modelling, hence the restriction on opening but I don’t know if they are opening too much to pass security.  I don’t want bars or grills on the window.

 

Notes on calculations

All windows are single pane and top hung, which gives me only one ventilation area for each window opening.

Glazing area is calculated as Window openings less 10mm packer and 53mm Frame.

Opening pane is calculated as window openings less 10mm packer.

53mm frame is similar to Velfac and Ideal combi rather than Rationel and Origin OW80 casement type window.  I could recalculate with larger frame.

Max stroke length of .650 (arms reach) has been applied to most windows reducing opening angle, they were originally meant to be fixed picture windows.

 

Ideas on ways of passing Part O

Sill heights have been increased already.

Change windows from opening outwards to opening inwards, the arms reach criteria means I can now open my windows more. What is the opening angle of an opening inwards window e.g Zylefenster?  Do I model as 70⁰? I shall look into this tomorrow.

I could somebody to do dynamic modelling to include MVHR and solar control glazing. Recommendations for dynamic modelling companies are welcome.

 

 

[Canski]

On 06/02/2023 at 19:46, Susie said:

  I don’t know how much the dynamic modelling would cost but would hopefully not be as much as changing all my fixed windows to opening windows.

 

I had a quote for £900 plus VAT for mine against £200 for the simplified method.  They were  very thorough, helpful and communicative when they did my SAP calcs. and I would recommend them. RJ energy consultants Ltd.

[IanR]

You've said "no" to 'Shading provided', but your three large windows on the Southern façade appear to have an overhang, which would provide good summer shading to those windows.

 

If you need more shading, you could consider external blinds on the 3 windows on the Eastern façade. They need to be automated to be effective, so it's not the cheapest option, but should be able to be hidden under the cladding, so no need for any planning changes.

Edited February 6, 2023 by IanR

[Canski]

on the subject of blinds .. would they need to be external or would the integrated blinds commonly used in bifold doors suffice ? I had some on my old house and they seemed to keep a lot of solar gain at bay.

[IanR]

I didn't look too much into integral blinds. Internorm at the time only offered blinds on opening sashes, and they were then between the 3G unit and a 4th pane.

Norsken, who I was also considering, did offer them within the sealed unit, but I felt the cable going out through the spacer was an unneeded risk to the unit.

I do wonder if there's likely more radiated heat from a blind within the unit, especially for a dark blind.

Integral blinds were also more costly than external blinds. 

[Susie]

1 hour ago, IanR said:

You've said "no" to 'Shading provided', but your three large windows on the Southern façade appear to have an overhang, which would provide good summer shading to those windows.

 

If you need more shading, you could consider external blinds on the 3 windows on the Eastern façade. They need to be automated to be effective, so it's not the cheapest option, but should be able to be hidden under the cladding, so no need for any planning changes.

The shading required is a bit misleading I live in a medium risk area and so do not require shading. The target is no shading and my answer to shading provided? Is no

if I was in London for example in a high risk area I might be required to have shading my target would be yes to shading and I would have to answer yes to providing shading, and it would have to meet set measurements. 
 

it’s a shame it doesn’t count in the simplified model but if I do pay for the dynamic modelling the overhang may be considered. 
 

[Susie]

On 06/02/2023 at 19:57, Canski said:

I had a quote for £900 plus VAT for mine against £200 for the simplified method.  They were  very thorough, helpful and communicative when they did my SAP calcs. and I would recommend them. RJ energy consultants Ltd.

 

I would be happy to pay £900 if they took the MVHR into consideration in the modelling before changing my fixed windows to opening.

I shall look up R J energy consultants

 

[SteamyTea]

Have you run the house though Jeremy Harris' spreadsheet?

 

Down here there is a chain on retailers called RJ.

Stands for Rubbish and Junk.

[Susie]

2 hours ago, SteamyTea said:

Have you run the house though Jeremy Harris' spreadsheet?

 

Down here there is a chain on retailers called RJ.

Stands for Rubbish and Junk.

I have used Jeremy Harris’ spreadsheet for heating. This is to pass Part O and it’s a real pain for a bungalow that is facing south for solar PV (and the views) but because it’s a bungalow has restrictions on night time opening of windows. I have to make every single window including the plant room open inwards to meet the arm’s length criteria but some are too high to open manually. 
it’s just a load more red tape for us small builders who have to pay to have another report done because we are so well air sealed we use MVHR for ventilation. 
If I was building a few houses I could model one dynamically as a so called worst case and use those results for all my builds. 
it looks like another grand for a bit of paper that is going to say my house has solar gain because it faces south but with MVHR it’s ok. 
that’s my middle of the day moan over.    

[SteamyTea]

5 minutes ago, Susie said:

looks like another grand for a bit of paper that is going to say my house has solar gain because it faces south but with MVHR it’s ok. 

Is there a recognised BSI standard qualification for that? You can probably submit your own calculations as I doubt a BCO would know how to check them.

Edited February 7, 2023 by SteamyTea

[Susie]

 

1 minute ago, SteamyTea said:

Is there a recognised BSI standard for that? You can probably submit your own calculations as I doubt a BCO would know how to check them.

I have been told by architect that because it’s new regs some people were fudging the results but BCO have caught on and are checking all spreadsheets on the simplified model throughly. 
 

got a company in Bude ringing me back later hopefully for the Dynamic modelling.

 

I need the software for the dynamic modelling as I just can’t pass the simplified modelling.  The simplified doesn’t take into account MVHR, shading by other buildings it designed into the build such as overhangs and canopies.  
For the dynamic method…

To demonstrate compliance using this method, there are a number of bits of guidance that must be followed, including:

1. CIBSE’s TM59 methodology for predicting overheating risk
2. The limits on the use of CIBSE’s TM59 methodology (set out in AD:O)
3. The acceptable strategies for reducing overheating risk (set out in AD:O

[SteamyTea]

Is this any help?

https://designbuilder.co.uk/helpv7.0/Content/_Ventilation_model_detail.htm#Natural2

[Susie]

Unfortunately no

its a bit similar to the SAP software I believe some architects are doing it in house others are farming it out. 
the advice is get it done before planning permission but guess what our local Architect got the planning first and then tells me he isn’t doing the new Overheating calculations that have to go to BCO before you start the build and is using a local company instead.  More delays. 

[craig]

Hi Susie, 

 

Thanks for sending the info through, I'll have a look into this but I really haven't dealt with this much but haven't read what I have and know what I know, this new part O is a pile of shite (excuse the French). Absolute joke and from reading others with a substantial amount more knowledge on this than me, they're of a similar opinion & the simplified method is far from simple.

[Susie]

Update

I finally have BC approval of my spreadsheet.

They accepted my first spreadsheet and the only condition was security on ground floor bedrooms, that are open at night, which I expected. 
The approval has dragged on due to a very slow architect.

I shall write more in my blog.