Search the Community

We have our planning permission but fall under the new regs so for Part O Overheating we have to pass either the simplified model or the dynamic model. I have created my own spreadsheet and by changing nearly all my windows to opening and to opening inwards to get round the arms reach criteria and a few minor size changes to increase ventilation we have just scraped through as a pass. My architect has given me my sketchup file and this weekend I plan to start looking at the Thermal Dynamic modelling TM59 with Part O adjustments using TAS software. The simplified model does not take into account the MVHR or the overhang shading so I am hoping by spending a bit of time and money on the software I can keep some of my fixed windows. As this is a new reg if any one wants to look at my spreadsheet I have attached it below. I’m a Mac user so if you run into any problems on Microsoft excel let me know and I can amend it. Thanks @craigfor your help so far. It’s been a steep learning curve to get this far so if I can help any one else on their journey that would be nice. So I’m off to start another steep learning curve using the software, just preparing with a big breakfast and lots of coffee. Any tips on the software welcome. https://kb.goodhomes.org.uk/wp-content/uploads/2022/07/220720_FHH-Part-O-guidance-Final-LT.pdf#page44 https://www.edsl.net/tas-engineering-downloads/ Part O Calculations Simplified method.xlsx

The UK gov released their consultation into incrementally green building standards a couple of week ago - link here: https://www.gov.uk/government/consultations/the-future-homes-and-buildings-standards-2023-consultation/the-future-homes-and-buildings-standards-2023-consultation#scope-of-consultation I guess the main takeaways will be the probability of mandatory heat pumps and possibility of mandatory solar panels? I can't claim to understand fully the changes to SAP calcs. Just wondered what the feeling was around the proposals? Missed opportunity? Positive? Unambitious? All you'd hoped for?

My previous blog entry ended at submitting the building regs in March, although they were not validated until 5th April and then refused on the 31st May. I believe my architect had complained on them taking too long so I am guessing when they found he had not included a turning circle for a fire engine they refused them as giving the architect extra time would have hit their own time targets. We resubmitted 1st June and finally had approval on the 5th July. A few conditions but nothing unexpected. In the meantime we submitted our amendment to planning for our window changes this was to increase the airflow through the house to pass Part O more on this later. This was submitted to planning on the 21st March and approved on the 12th May. When the BC plans were initially refused I decided not to contact our architect as he obviously had something wrong and as it was all out of my hands, I just presumed it was not my Part O spreadsheet as he never contacted me. You can not rush anything in Cornwall it will all be dealt with dreckly, (eventually no time limit). Instead I got on with jobs I could do, mainly starting a new vegetable plot as the old one is in the way of the new build for plant access and will eventually become garden. My potting shed is only a few years old so it will be dismantled and stored indoors until we have walls and roof on and can position the shed close to the new build. My netted tunnel is also now down and will not be going back up instead I will create new smaller structures to cover individual groups of crop and re-use the larger netting just for my new strawberry beds. We have had a hosepipe ban on here in Cornwall for a year now so it’s not been a bad year to not be growing anything new and instead concentrate on the soil and new beds. Top photos are the early days of my vegplot and below as it is now, looking a bit sad but better things will come. Before it sounds like I’ve lost the plot and writing a gardening blog I’ll return to our build progress. We advertised our existing barn as free locally and received many offers to remove it. A local couple will be taking it down in October and rebuilding it on their land. I’ve sold a lot of paving that I had kept just in case we wanted it in the future but finally decided it’s not required. The problem with having land and outbuildings is it’s difficult to get rid of things we just move it to the cow shed but that has to stop. So all the wood in the old cow shed is moving to the old pig sty. We started keeping the wood because we wanted a stove but eventually decided our listed barn was never going to have a wood stove so a few trees that got cut down were given to neighbours but now the new build is going to have a wood stove so we’re saving wood again. Emptying the cow shed also involves giving away corrugated tin roof sections that have been saved just in case, moving a pile of nice small stone I was going to make a rockery with and finding a new home for our Christmas wooden reindeer. The cow shed is now nearly empty. We also hired some plant and shifted some spoil full of weeds from around the cow shed and took down two more trees, the Ash tree had Ash die back and it had been allowed to self seed much to close to the fir tree that had grown one sided. They were also in the way of the new field access that we are making wider for easier machinery access, and will also now provide a hammerhead turn for a fire engine. The spoil and tree stumps were moved to the lower field, the useable fire wood stored in the old pig sty with a few large pieces left as temporary seats for the builders. Top row left cow shed surrounded by weeds, right new wider access cow shed on the left with stables in the distance. Middle row clearing in progress and the better access. Bottom row me in the sun and heat while husband is in the Air Conditioned digger, some of the larger stone put to one side no boulders so far. We still have not got our ground-workers or builders sorted out, a few have been to look, some you never hear from again others give a quote that’s ridiculously high with so many provisions. Some will do this and that but not that, they suggest somebody else who is not interested. I think it's partly because we want an ICF build and also to dry shell stage only, excluding windows. We still hope to start next year but are now thinking to just get the groundworks completed as that is the most unknown quantity, and we are still saving up. The build is being partly funded by the sale of a Jensen FF but we have only just got round to advertising it last month and finding the right buyer could take a while. Part O Unfortunately my architect did not think ahead and design the house with Part O in mind and it took quite a while for me to work out what I had to change to pass the simplified method. A local company was approached and discussed the simplified method and the dynamic method but from what they told me there was no guarantee in passing either and to pass the dynamic method more changes to the building design and further dynamic modelling could be required so no set fee was offered. Instead I designed my own spreadsheet that initially proved our ventilation of just opening windows would not be enough to pass Part O but after reading up more and few window swapping ideas I got a pass on my own spreadsheet. I also stumbled upon the future homes site which has a spreadsheet that can be downloaded. As I’m a Apple Mac user it meant using MS Excel online but it was a far prettier version than my nuts and bolts spreadsheet and one that I thought my BC would be happier with. I input my window measurements and how they opened, and obtained a pass. Anybody reading this and wanting ideas on how to pass the simplified method first depends on what you fail on e.g. too much glazing or the free flow of ventilation although one can impact the other. I don’t think anybody looking at our plans from the first blog would think we would not pass as the southerly view is not overly glazed but by removing 3 windows on the northerly side and adding 6 roof windows that open 50 degrees and slight changes to bedroom windows meant the northerly facade was the most glazed and we had better air flow. We also changed all windows that open to open inwards to meet the arms reach criteria, enabling a wider opening. The spreadsheet is not perfect though as my bedroom windows are tilt and turn but you can only have the same hinge for day and night on the spreadsheet e.g. side hung. I could have adapted the spreadsheet but that would mean its not as trustable as I was hoping it was going to be or I could have created two one daytime side hung and one for night time opening when the windows are top hung. I decided to make the one spreadsheet work as explaining to my architect who would then have to explain to BC would be like learning and then teaching a foreign language. Happily we passed the simplified method with a condition about night time security when I get my own named BC I will be able to talk them though the spreadsheet quickly change the side hung to top hung and get a pass and if I still need a security grill it will only be for the lower half that opens at night and this can be made to measure by my talented husband out of rebar. The changes to windows did mean we had to make an amendment to the plans but as it was due to my architect not thinking ahead about the new regulations I suggested to him that I shouldn’t have to pay for this and he agreed. https://www.futurehomes.org.uk/library#Guidancetoolsandtemplates SAP When you start out on this journey there are so many new things to learn about and discover the pre build SAP being just one of them. Unfortunately this area seems controlled by a piece of software probably not much more than a spreadsheet but no free copy for us self builders to play with to see if we change x how does it effect y etc. I was in the hands of my Architect and if you haven’t worked out by now I am usually in charge of everything so taking a back seat I found very hard. The initial SAP needed a few tweaks here and there but Im happy with the result. For those of you who don’t know what one is I am attaching mine and if anybody wants to dissect it feel free to do so but the pages long report is quite boring as they all are and it comes down to insulation, air tightness and your chosen method of heating. We plan to have a minimum of 11kw of Solar on our virtually perfect south facing unshaded roof in Cornwall. This and together with an ICF build and good window air tightness with lots of added floor insulation hopefully will mean low running costs. You will not find a ASHP mentioned I’m not having one. I don’t like them for my build. I’m near the sea where everything rusts, and if I need a plumber because its broken it will be 6 weeks before one would be available who knows enough about ASHP to fix it. In the 6 years I lived in Cornwall I have seen the lack of trades people first hand in waiting for returned phone calls that never happen, quotes that take ages and waiting lists for the good people. In winter when you most need good heating then all the trades are busy working in the holiday homes out of season and are booked up. We have no mains Gas so are going to be a mainly electric home. To ride out the peaks and troughs of solar we will have as much on the roof as we can fit and rather than export to the grid we will export to our other working barn and lower some of those summer electricity costs. In winter we will have to buy some electricity but hopefully very little at peak costs. Quick guide to the SAP The first 3 pages are our planned u-values, expected Air permeability results, space heating, hot water etc and MVHR. The following 30 pages look very similar but have different headings and figures. Calculation of dwelling emissions for regulation compliance Calculation of target emissions Calculation of fabric energy efficiency Calculation of target fabric energy efficiency Calculation of energy rating Calculation of EPC costs, emissions and primary energy page 18 perhaps the one to read first Calculation of energy rating for improved dwelling Calculation of EPC costs, emissions and primary energy for improved dwelling Finally the predicted energy assessment on page 33 (96A0 and the estimated energy cost for the property over a year £103 That’s all for now, my next job is getting a full online estimate of the build now we have all the building regs and SE calculations completed. Build Costs b/f from first blog £12660 Building regs submission £345 Hired in plant and fuel £890 SAP £300 Part O Free VAT element only on building regs, and SE (Not included in first blog totals) £430 Total to date £14625 SAP.pdf Part O.xlsx

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.