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Posted

I don't suppose anyone here has a copy of WUFI Pro and would be willing to run some calcs for me, would they?

The architect wants to use hemp block as part of the build-up for some flint-and-lime walls. The manufacturer doesn't have WUFI data available, so we were going to run the calcs ourselves to make sure we won't ha ve a problem with condensation. Only problem is that the free version of their software doesn't allow you to specify custom materials, which means I'd need to pay €1k for a year-long license when it's only a quick job that needs doing.

Posted

I worked my way through this on our build and in the end I chose to get a professional to do the calcs for me and then give me a full report which is a sort of guarantee that the design is sound. The cost was less than the licence as I recall and de-risked our journey through that bit of the design.

Posted

Ta @MikeSharp01! Can you make a recommendation of the folks you used?

I'm going to ask the architect to ask the supplier if they want to contribute towards the cost, seeing as the information will be useful for their future sales and marketing.

Posted
1 hour ago, Drellingore said:

Can you make a recommendation of the folks you used?

I will dig it out - I think I mentioned it here probably 6+ years ago.

  • Thanks 1
Posted

I experimented with WUFI intensively while I had temporary access to it, but I don't have a license so can't help directly.

 

However, it's important to know that WUFI's results are highly dependent on the internal environment (temperature and humidity) used in the modelling. Getting that right isn't easy (unless other software is used to create a model the building's environment first) as there's a lack of published information on the topic. In short, it may not be a quick or cheap job to get realistic results, especially if you're planning to 'modify' the internal environment with MVHR.

 

Some of the issues discussed here:

 

 

 

  • Thanks 1
Posted

Many years ago when I was adding extra insulation to my loft, I created a condensation  risk spreadsheet.

Seem to remember it was pretty basic, but as I have not had any problems in 18 years, it must have been accurate enough.

 

  • Like 1
Posted

We think it'll be fine - the hemp block is apparently more water-permeable than wood fibre for the same U-value. It's a shame I can't do it on the free app, because getting additional confidence would be worth paying the price of an hour of ChatGPT guiding me through the process. I'm not sure that peace of mind will be worth a €1k software licence though!

Posted
12 minutes ago, SteamyTea said:

How much you spending on your build.

 

If you care about the pennies, the pounds look after themselves! Or something.

Posted
1 minute ago, Drellingore said:

 

If you care about the pennies, the pounds look after themselves! Or something.

Yes, I work for penny punching people.

Posted
Just now, Drellingore said:

 

Does Penny ask you to punch a lot of people? 😆

I am mentally punching customers, and staff, every hour of the day.

  • Haha 1
Posted
10 minutes ago, Drellingore said:

 

If you care about the pennies, the pounds look after themselves! Or something

The chap we used was from Umbay. Energy & Design Services info@umbay.co.uk. The final invoice was only a couple of hundred. 

  • Thanks 1
Posted

Worth having a scout around the inter web and see if there is a crack available.

Many software packages use the same algorithm for key codes.

Posted
12 minutes ago, SteamyTea said:

Worth having a scout around the inter web and see if there is a crack available.

Many software packages use the same algorithm for key codes.

If you do this run it in a VM. Cracks / keygens are a great place for "added value"

Posted

I wouldn't get too hung up on WiFi or any other modelling tool. It is powerful software but it is only as good as the build of the house. 

 

 

The golden rule is that a building must consistently dry faster than it accumulates moisture. 

 

In priority order:

 

1. Eliminate bulk water infiltration from gutters, roof leaks, driving rain, high water tables etc. 

 

2. Establish proper ventilation to control internal humidity levels. Mechanical is best, eg DCV or MVHR. 

 

3. Airtightness. Drafts carry moisture laden internal air into the structure where it condenses and causes issues. It out weights the effects of diffusion driven moisture by over a factor of 100. 

 

4. Take care with layering vapour impermeable materials. They really hinder drying if done incorrectly . 

 

 

Permeable and "breathable" materials are not a Panacea. They will not compensate for ignoring the above principles. 

 

 

 

 

 

 

Posted

FYI - you can put your own materials into the free version of Ubakhus. For the sake of 10 mins work, it would be worth running the condensation calcs there as a start.

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