BS-5839 part 6 LD3

Dwelling fires are still falling in England from 28,504 in 2019/2020 to 25,408 in 2024/2025. That said the number of fatalities is creeping up 194 in 2024/2025 compared to 166 in 2023/2024 and 199 in 2022/2023

(source assets.publishing.service.gov.uk/.../FIRE0205.xlsx)

The guidance that supports the building regulations ADB v1 still up to 2029 only requires LD3.

BS 5839-6 does recommend a risk assessment before picking a category. And categories are short hand not straight jackets adding a extra detector does mean its becomes another category.

BS 5839-1:2019 + A1:2020 recommends LD2 for new dwellings. Plus it is starting its review in January so start your ideas on how it should be changed now!

Will Lloyd said:

BS 5839-1:2019 + A1:2020 recommends LD2 for new dwellings. Plus it is starting its review in January so start your ideas on how it should be changed now!

It also recommends a minimum of LD2 for (existing) rented properties and owner-occupied larger homes.

This year, my insurers obliged me to installed interlinked detectors/alarms. On the basis that their next step might be to require mains-driven ones, I installed them.

In an existing dwelling, moving furniture, taking up carpets and floorboards, etc. is a real faff, but given that the cost of installing the cables is negligible, why would you not do that in a new build?

Part J of Schedule 1 of the Building Regulations 2010 requires carbon monoxide alarms where there are combustion appliances in domestic premises. Part B is more vague: B1. The building shall be designed and constructed so that there are appropriate provisions for the early warning of fire ...

It seems odd that detectors/alarms are not explicitly required in rooms containing combustion appliances.

The only time when this house came close to being set on fire was when Mrs forgot something under the grill. The flames were touching the ceiling.

So in answer to Sergio's question, I would go for LD3+, i.e. LD3 as it is plus an detector/alarm in any room which contains a combustion appliance, plus the kitchen; and all alarms to be mains-powered and interlinked.

Chris Pearson said:

In an existing dwelling, moving furniture, taking up carpets and floorboards, etc. is a real faff, but given that the cost of installing the cables is negligible, why would you not do that in a new build?

in a word money

the extra cost of a couple of extra smoke/heat alarms is lobbied agaist by the house building industry. to change things goverment has to do an impact assessment and they don't like things that add cost

Chris Pearson said:

In an existing dwelling, moving furniture, taking up carpets and floorboards, etc. is a real faff, but given that the cost of installing the cables is negligible, why would you not do that in a new build?

in a word money

the extra cost of a couple of extra smoke/heat alarms is lobbied agaist by the house building industry. to change things goverment has to do an impact assessment and they don't like things that add cost

"in a word money."

Quite, and if labour was free and materials were free, we'd all live in mansions with hot and cold running servants.  Oddly we don't.
And the question then becomes more nuanced - 'what is this measure worth?' and of course ' could we do more good overall if we spent the same money elsewhere?' And this is a painful balance for some because although folks will say one death is too many (and perhaps if it is them or their loved one whose life was lost, it is) you cannot design a policy based on that. If we did, then maybe  we'd still have a man with a red flag walking in front of every car and electricity and gas would be banned.

What changes over time is what level of protection is cost -effective, and rather like what sort of medicines the NHS will pay for, that depends partly on the value placed on a life and partly on how the materials cost tend to fall over time.
So If you think one life saved is say 1 million pounds (and that is probably not true but hey ho), but installing a basic fire detection system costs say £50 (battery smoke alarms on double sided tape) then only one in every 20,000 such systems needs to save a life for the exercise to have been worthwhile. But a more complex  system costing say £500 to install is not worthwhile unless you can be sure that for every 2000 systems you install, a life is saved. 
As noted cost to retrofit is far higher than to fit to new build, but even new build the cost is still not zero.
But things like wireless linked bases may lower the cost of something more sophisticated that was once too expensive, back to being worthwhile again.

So what has changed in terms of cost per given efficacy, and have we raised the value of life ?
I'm not trying to be callous, but this is the way to prove you are not squandering money on fire alarms that may have been better spent on (say) water temperature alarms or anti mould measures or some other non-electrical matter.
The usual problem is we don't usually have enough data to be sure until after the decision has been implemented.
Mike.

mapj1 said:

What changes over time is what level of protection is cost -effective, and rather like what sort of medicines the NHS will pay for, that depends partly on the value placed on a life and partly on how the materials cost tend to fall over time.
So If you think one life saved is say 1 million pounds (and that is probably not true but hey ho), but installing a basic fire detection system costs say £50 (battery smoke alarms on double sided tape) then only one in every 20,000 such systems needs to save a life for the exercise to have been worthwhile. But a more complex  system costing say £500 to install is not worthwhile unless you can be sure that for every 2000 systems you install, a life is saved. 
As noted cost to retrofit is far higher than to fit to new build, but even new build the cost is still not zero.
But things like wireless linked bases may lower the cost of something more sophisticated that was once too expensive, back to being worthwhile again.

Not sure I fully agree there Mike.  When I was growing up in the UK in the 1970 and 80s few house domestic houses had smoke alarms.  Any that did probably only had 1 for the whole house.  Now in the 1980 I remember campaigns to get a smoke alarm for your home for your family safety.   BUT the push became significantly stronger in the 1990s following new UK building regulations.  

These days people understand from past history/campaigns/building regulations and general awareness that 2 smoke alarms in the average 3 bed semi is more prudent.  I do agree that the cost of smoke alarms has reduced.  

As an example

Screwfix do a battery operated smoke alarm £6.99 as it most basic offering (Smith & Locke KD-129H Battery Standalone Smoke Alarm (747CG))

or 

Hispec Fast Fix PE/FF Mains Interlinked Optical Smoke Alarm (361RG)  £18.50

Other brands and other wholesalers are availabel

Thus for less than £100 you could get 3 interlinked mains units with battery backup for an average domestic dwelling.  IF mains power is cost prohibative due to labour or build fabric them battery power and interlinked is still an option but fractionally more exspensive but lets say less the £150.  So I put it to you and the community at large.  

What is the cost/value of the/a person for an average 3 bed semi against £150.  Remember, people are not just values or numbers, they are someones family or loved ones.

mapj1 said:

What changes over time is what level of protection is cost -effective, and rather like what sort of medicines the NHS will pay for, that depends partly on the value placed on a life and partly on how the materials cost tend to fall over time.
So If you think one life saved is say 1 million pounds (and that is probably not true but hey ho), but installing a basic fire detection system costs say £50 (battery smoke alarms on double sided tape) then only one in every 20,000 such systems needs to save a life for the exercise to have been worthwhile. But a more complex  system costing say £500 to install is not worthwhile unless you can be sure that for every 2000 systems you install, a life is saved.

I have a figure of £1m at the back of my mind, but we could say £2m to account for inflation.

These alarms do not prevent fires, nor do they put them out. We could add injuries to people and property to the equation, but it seems that the BS 5839 systems are intended to allow occupants (more) time to escape. So, if the aim is to reduce mortality, it begins to look like a public health question and it is indeed, "rather like what sort of medicines the NHS will pay for".

It seems beyond doubt that reducing excessive blood pressure (hypertension) reduces the risk of stroke and heart attack. If a pharmaceutical company wanted to bring a new anti-hypertensive to the market, it would have to show that it was more effective (in terms of mortality or morbidity) or at least as effective, but cheaper than existing drugs. So they are not comparing new drug against nothing, but new against old. Undoubtedly, a randomised controlled trial would be involved from which number needed to treat could be calculated.

Similarly, one could compare LD2 and LD3 protection: how many LD2 systems need to be installed to save one extra life?

But now we have a problem. Could we do a randomised controlled trial? One of the Government's proposed new towns would do. Fit half the properties to LD2 and half to LD3. Then, ignoring any ethical considerations, wait 50 years and hope that sufficient fires break out to allow a meaningful comparison.

What is the cost/value of the/a person for an average 3 bed semi against £150.  Remember, people are not just values or numbers, they are someones family or loved ones.

So for say, 20 million houses in the UK (there may be more by now) that's £ 3 BILLION - what could be done with that sort of money? Cure for another cancer? Thousands of urgent operations brought forward? Better care for the elderly? Are you going to tell their loved ones that they're less worthy than a plastic box on loads of people's ceiling's that 99.99% of the time provides no benefit whatsoever?

No easy answers.

  - Andy.

I am not sure why it would cost the government or the people £ 3 BILLION.  As I stated previously you could get the kit from ScrewFix (other sellers are also available) for an interlinked system for between £100 to £200 for the average 3 bed semi 

 Afraid that Andy's figure seems to assume that nobody has any smoke detectors/alarms yet!

HMG promises to build (i.e. hoping that the private sector will build) 1.5 million homes during its 5 years in office. So at £150 a pop, that is £225 million.

One really good jackpot in the Lottery!!!

So the parts alone are £200, what does it cost to retrofit to a building and then make good ? I presume perhaps a day, maybe two, so more like 300-400 all up.  So we do that for 20 million house-holds and that is 20*300 = 6000 million, maybe 20*400 - 8000  so between  6-8 billion. You are right - it would be a serious investment.

Could we save enough extra  lives over the life of such an investment  (perhaps 10-20 years) compared to that money spent another way?  After all the folk dying from all the other things we don't do instead so we can afford to do just this are also someone else's loved ones. There is no truly free lunch. 

I'm not saying we should not uplift the recommended standards - far from it,  just that there is an argument for putting our money most carefully where it has most effect  - cost benefit analyses are not some obscure excuse not to do things, they do serve a very real purpose. We do need to be able to clearly justify why a more complex and expensive recommendation is to be preferred.

To my mind Chris's thought experiment is correct, but very hard to sell morally.

Mike. 

Afraid that Andy's figure seems to assume that nobody has any smoke detectors/alarms yet!

As a first approximation yes. But then consider that most alarms seem to come with a recommendation to replace after 7-10 years ... so you might then see the £3B as being less of a one-off investment, but an every decade recurring cost.

   - Andy.

The current government (Labour) came into power July 2024 with the ambition of 1.5 million new homes during their term in parliament.  The next general election must be called by August 2029. The general election MAY be called earlier.  I very much doubt they(Labour) or any UK government can achieve this objective during A/The 5 year Parliamentary term.  This point is however mute in this discussion as all new design and builds for domestic dwellings need/will need to meet an LD2 category due to
BS7671
BS5839
Building regulation and Approved Documents.  

The LD3 category would only really affect the existing housing stock in the UK except for Scotland.  Now of that, roughly 25 million housing stock in England about 1/3 are rented.  Thus they will/SHOULD be covered by things like PRS (Private Rented Sector) and social housing.