SteamyTea

There was a radio program about PR people and journalists. Very interesting. https://www.bbc.co.uk/programmes/m001y9pt

With booze you loose, with dope you hope

A while back (I don't like to rush things) I got into a debate (spat if you like) about cheap lightweight saucepans on induction hobs. My view is that they are fine, no need to go for "heavy bottoms': learning to cook makes the difference, not the pan. So today, after reading a science article about just this very point, I thought I would look at the thermal distribution on my cheap pan and my expensive pan. Well as far as I am concerned there is not enough variation to make any difference. Here is the video. Cheap saucepan on the left.

I think we may be at cross purposes. I was not calculating the P/A ratio, just the thermal losses in a first order simplified manner.

Yes, I have just realised I mistypes and was about to go and edit it. Fixed now, it works out as a total floor area of 83.6m2 because the periphery area is 3.6m2. (10m + 10m + 8m + 8m) x 0.1m = 36m * 0.1m = 3.6m

I did a calculation on this a while back. Convert the 3D shape into a 2D topological shape i.e. work out the area of the periphery and add it to the floor area. Then just calculate as normal. So say your floor is 8m by 10m and 0.1m thick. A = 80 [m2] PA = 3.6 [m2] TA = A + PA = 83.6 m2 Multiply by U-Value. PIR k-Value = 0.022 [W.m-1.K-1] R-Value = 0.1 [m] / 0.022 [W.m-1.K-1] U-Value = 1 / ( 0.1 [m] / 0.022 [W.m-1.K-1]) U-Value = 0.22 W.M-2.K-1 Then add/subtract for joists area and properties.

I found this simplified method online IP 3/90 formula U = 0.05 + 1.65(P/A) - 0.6(P/A)2 Where: U = U-value of the uninsulated floor (W/m2K). P = Length of the exposed perimeter (m). A = Area of the floor (m2) https://cms.esi.info/Media/documents/Warma_UvaluesUFH_ML.pdf I am not sure if it is right, the final number, 2, could possibly be 2 Apart from that, it is easy enough. It would be nice to know what the real formula is.

As anhydrous mean not containing water, what is used to make the cement set?

This is the problem with using initials/acronyms/abbreviations. Even after being involved in the plastic industry since the 1970s, I still get confused as to what people are really talking about. Phenol based plastics were usually referred to as PFs, polyurethanes as PUs, polystyrenes as PSs, polyethylene as PEs. Then the processing method makes it even harder, so expanded is E, but extruded is X. Then it all goes wrong with materials like PIR, I can just about accept the PI bit for polyisocyanurate, but why the R at the end.

https://www.bbc.co.uk/news/uk-scotland-68841141 How often have I said that in the UK for every rule that says we must do something, we have another one that says we must not do it.

BS 7671:2018 https://electrical.theiet.org/wiring-matters/years/2019/77-september-2019/bs-76712018-frequently-asked-questions/ Half a meter deep at least.

It might be, but engineering is not all about catastrophic failure. Acceptable deflection is important as a constant tiny movement can cause problems i.e. rattling or leaks. Ah, the old screw and bolt debate. Regardless of what others say, screws and bolts are different things, that work in a different way, not a case of one is better than the other, they are different and should not, in isolation, be compared to each other.

That is about half a bath

What are they. You can get condensation at very low RH levels.

There is always gill nets, they wash up on the shore often enough.

Would those ground mats that are used for vehicle parking work?

Welcome As others have said, what does that actually mean? In the 'olden days' buildings relied on a fire (usually open) to draw air up a chimney, that air was replaced by uncontrolled leaks in the building fabric. Since we got rid of open fires (though there is still a lot of people that think they are the greatest thing invented) and fitted heating systems, we have relied on those original, uncontrolled fabric leaks to ventilate our properties. As building standards and techniques have improved, generally our airtightness has got better. This has caused a problem with internal humidity becoming higher and causing mould growth and general air stuffiness. To get around this more ventilation, but more controllable, has been introduced. This is usually though window trickle vents and air bricks. While this change was happening, there was little regard to energy usage, so we fitted larger heating systems. This seemed to work in the majority of homes, but, and this is an important but, if it is not used correctly i.e. heating on for only a few hours a day, a yoyo affect happens with the temperature rising a falling, which changes the relative humidity. This in turn changes the dew point temperature and the water vapour that is naturally in the air (from people, cooking, washing, drying clothes and pot plants), this water vapour can now condense to liquid water on cold surfaces and cause an environment that is ideal for mould growth. So just changing the air may not cure all the problems. To get around the problem, many people fit mechanical ventilation in bathrooms and kitchens. These units generally are oversized and shift a lot of air. 1 litre per second of air is converts to 4.5 kg of air per hour. Cheap fans can easily shift 30 l/s. Now the trouble starts when a fan is fitted with no regard to the original leakiness of the building. Because replacement air has to enter the building somewhere, and will take the path of least resistance, it is possible to create cold spots around these leaks, this is where mould will starts. This is not really a problem if they are visible and they can be dealt with on a regular basis, but if they are hidden, they become a problem as the air movement that is naturally there will distribute the mould spores. It is those spores that are the problem. This is why 'positive pressure' systems are often fitted, they are designed to blow outside air (I will not call it clean air) into a building in a controlled fashion. That new air needs to find a path out the building, and it does it via the holes in the building fabric. Often this is not a problem, but occasionally it can exit into an area what can cause problems and then condense, creating a mould problem that can start to rot the fabric of the building. To get around this, modern houses are designed to be airtight, and then only known exit points all the inside air to leave (you can read up on vapour control layers and wind tight membranes, it is a huge subject and very misunderstood). That is a bit of background (and unedited for clarity). So just pumping in air, or extracting air, may not solve the problems on its own, and can cause energy usage to increase. To reduce energy usage, mechanical extraction is often fitted with heat recovery (heat is the old word for energy). These help keep bills lower as they can recover approximately 80% of the energy that would be lost in the expelled air and reintroduce it into the replacement air (again, I hesitate to say clean air). The trouble is that it does nothing to change the existing leakiness of the building, so those thermal losses have to be added to whatever losses the MVHR (mechanical ventilation and heat recovery) losses are. If that is not taken into account when designing a system then performance can seem disappointing. If you want to deal with this problem, then the first thing you need to do is get an air tightness test done and fix all the leaks you can. This can be expensive, but does give you a known base to work from, and solves all those small places that mould can grow. Then you can fit just about any mechanical ventilation system and start to see benefits. As you are in London, which is a big place with varied air quality, the type of filters used becomes important. It is relatively easy to filter out pollens, but fungal spores are a lot smaller, so harder to filter out, gases like Nox are smaller still, PM10 to PM1 are similar sizes sores, so virtually impossible to mechanically filter. You have to stop fungus growing and being distributed indoors. All seems a bit doom and gloomy, and expensive, but you can make improvements. (I suffer really badly from allergies and they virtually disappeared, apart from seasonal hayfever and to animals, when I moved to 2 miles from the Cornish coast from Hertfordshire)

Very good https://en.wikipedia.org/wiki/Mohr's_circle

I am off to Buckinghamshire tomorrow, if there is any on the way I can pick it up.

They carry on using them until it becomes economically viable to replace them. Then the old modules are sent for recycling or sold cheap for other projects. In the past they have gone to either landfill where they very slowly degrade or they are reconditioned, reprocessed or ground up to make fillers. There is a bit of a myth that composite plastics cannot be recycled. We were recycling our waste back in the 1970s. I wonder what happens to all the emissions for combustion technologies. While my car is considered a 'clean diesel' and better than previous models, I don't tow a barrage balloon behind me connected to the exhaust for later conversion to another product or fuel.

Got to be cheaper than not knowing what is causing it, or having to get an electrician out.

This is why you have to have blanket rules and laws.

They have valleys in rural areas, in fact it is where most people live. Last year I posted a picture up of the Hayle Estuary covered in smog from all the wood burners.

I don't mind at all. I like to drive fast around corners until my tyres squeal. Not considered acceptable.

Not really. They can burn bottled gas or oil, which probably is less environmentally damaging overall (but only because we already have the infrastructure to produce and distribute it). It will absorb less CO2 than a mature tree by m2. Well not chemically. This is one of the misunderstandings. The atmosphere is a shared resource, tinker with it too much and unexpected things happen. Take the last 6 months in the UK, we have had double our usual rainfall. Now many people will say this is natural variation, or it is because we are in an El Nino period. But double. We have also had another mild winter, I think the last 3 months were record breaking. We just need to stop burning.