SBMS

Thanks @Iceverge

Would you recommend a particular EPS bead product?

We are looking at a brick and block construction with a 150mm cavity. What experience has everyone got with the above option and can anyone recommend a particular insulation method for a 150mm cavity? At the moment am favouring a blown in product as it’s guaranteed 100% coverage but would be interested to hear peoples thoughts on price and performance?

In a traditional brick and block construction what’s the consensus on the main areas where airtightness can be lost? Our SAP guys have gone for an air change of 4 which is clearly higher than I would like. With well fitted doors and windows, warm roof and plasterboard on dot and dab, what sort of a difference might we expect with a well built shell? I know recommendation is wet plaster and parging between floors but I wondered if there are any real world examples from members where dot and dab and no parging were used?

@joe90 Can you share your Air permeability test/changes per hour?

@Iceverge Quickly read the mentioned topic, but what's the rationale in a nutshell? If you have a good builder who can fit PIR well onto the inner leaf is there any reason you would still recommend full fill mineral?

@ProDaveThanks, that makes sense. The coldest day value (+20, -10) is coming out at around 7776 (7.7kW), average is around 4.1kW. A worst case scenario for an ASHP generating 184kWh of heat in a 24hr period, would be 61kWh of electricity (or £12). Thats a whopping bill of £380! But I guess this is extremely unlikely. I also don't think Jeremy's spreadsheet makes a huge amount of sense for summer values? i.e. we never have any central heating on from around May to September, so in theory there's a 0kWh requirement in these months, but this isn't what the spreadsheet is showing. Is that typical with an ASHP too? Also - am I right in thinking that a worst case of 7.7kW would require an 8kW ASHP?

Just thought I'd send some appreciation for his work on it.

Hi all Thanks @Jeremy Harris for your useful calculator. I'm just trying to get my head around some of the numbers so we can assess different insulation levels, double vs trouble glazing etc. I just wanted to make sure I am reading the calculator correctly! I've plumbed in the following values: Air changes per hour = 4 MVHR efficiency = 85% Wall U value = 0.19 Floor U value = 0.1 Roof U value = 0.16 Average window U value = 0.8 Average door U value = 1.2 Average roof light U value = 1.3 Along with the following dimensions of our property Internal wall area = 272.00 m2 Internal roof area = 125.00 m2 Internal floor area = 128.00 m2 House total internal volume = 700 m³ Its a 2.5 storey house, 240 total square meters and I've used an online calculator to ascertain the internal volume using our working drawings. It appears to be generating a space heating requirement of 23,933kWh per annum for average OAT (the sum of row 84). This is giving an average cost per square meter to heat of about £100. This seems really high, but perhaps I am misreading or misunderstanding? I am effectively trying to work back from this to understand the electricity costs for an ASHP to heat this space. It seems that the "Total daily heat loss power for average OAT (W)" is coming out at 4109W (4.1kW), but then it seems that this value is multiplied by 24, so I'm assuming this isn't the total Daily heat loss power, but the total Hourly heat loss power? Thanks in advance.

Got you. So effectively they're going off some 'stock' figures. I was going off ecotherm's calculator; https://uvaluecalculator.ecotherm.co.uk/calculator/walls/cavity wall/brick/lightweight (0.15)/3mm skim-coated 12.5mm plasterboard/partial fill/75/ which is the manufacturer @ our local merchants. Kingspan's calculator has a lower mark of 0.18 - both of these are better than the U Values used by the SAP calculator. I assume these would suffice as evidence?

This is the SAP calcs done by a firm, based on the above spec... Are you saying that they don't adjust the 'As Designed' Spec, to reflect the cavity solution described above?

Hi all We have received our first set of SAP Calcs back for our new build. The wall U-Values are coming out around 0.22 - this is using 100mm block, 100mm cavity with 75mm PIR, 100mm inner light block (just standard for now). However, putting this same spec into Kingspan/EcoTherm U-Value calculators, it spits out 0.17. Does the SAP Software calculate things differently? Thanks

That would make sense, and I guess would make it really clear that the authority had decided to impose an optional regulation. There weren't any conditions related to this in our planning approval, so I think we can inform BCO we don't need to adhere to these optional conditions.

Thanks for the responses. I've been told that there are "Optional Technical Housing Standards" which are standards local authorities can choose to apply or not (or that housebuilders can choose to optionally adhere to). The summary for these standards (and how they inter-relate with Building Regulations is): "In March 2015, following consultation on accessible design standards, the government issued policy in the form of a Written Ministerial Statement on housing standards. It introduced new additional optional Building Regulations on water and access, and new optional national space standards referred to as the ‘new national technical standards’. The new standards complement the mandatory Building Regulations 2010, SI 2010/2214." The example for water efficiency from the Govt's guidance on optional technical housing standards is this: "All new homes already have to meet the mandatory national standard set out in the Building Regulations (of 125 litres/person/day). Where there is a clear local need, local planning authorities can set out Local Plan policies requiring new dwellings to meet the tighter Building Regulations optional requirement of 110 litres/person/day." So it does indeed indicate that there are optional standards that complement Building Regulations that a new home can adhere to, but that may also be set at a local authority level as a mandatory requirement? I think I should have named this topic something better than 'optional part of building regulations' as these are not those, but are 'optional technical housing standards'! My question, for anyone that's come across this, is, can a local authority mandate them? The govt document I read is here: https://www.gov.uk/guidance/housing-optional-technical-standards

Hi all We are just kicking off our self-build and have appointed our private Building Control firm. They have asked us whether we are requiring: -regulation 36(2)(b) (optional water efficiency requirement of 110 litres per person per day), -Schedule 1 Part 1 optional requirement M4(3) (category 2- accessible and adoptable dwellings) Reading online it seems that these are optional parts of Building Regs that you can elect to comply with, but that some local authorities can mandate this? Is this correct, and how would we know if this was something our local authority insisted on? Further - if we are using private BCO - does the local authority have any input on these two in any event? We would, of course, prefer not to elect to comply with these, but interested to hear other's thoughts!