MVHR vs Air Con - if you had to pick one?

[Nickfromwales]

19 minutes ago, saveasteading said:

Like all those miserable people in the Mediterranean climate. It's OK.

They get it all year round. We don’t .

[Thorfun]

1 hour ago, tuftythesquirrel said:

We have a SE (18m) and a SW (22m) facing aspects and don’t need AC. If we know that it going to be 30C+ we actually keep the windows closed and use blinds to limit the solar gain. We very rarely get above 23C. So it can be done.

I like to look out at the blue sky so have AC to allow that if I wish to! We also have blinds to help with overheating but I don’t want to live in a house in permanent shade during the summer months. 

[SBMS]

I considered whether to install AC or not but have decided to fit fancoils to the first floor bedrooms and landing areas and have a two zone ASHP system. So can cool to proper AC levels in summer if needed. Wasn’t hugely more than a standard ASHP and was roughly the same as not doing UFH upstairs. And installed MVHR as well. 

[Thorfun]

17 minutes ago, SBMS said:

I considered whether to install AC or not but have decided to fit fancoils to the first floor bedrooms and landing areas and have a two zone ASHP system. So can cool to proper AC levels in summer if needed. Wasn’t hugely more than a standard ASHP and was roughly the same as not doing UFH upstairs. And installed MVHR as well. 

But can’t cool while the hot water tank is heating, right?

 

I also considered fan coils and floor cooling but it was getting complicated and seemed like a lot of faff. 
 

having separate AC and ASHP just kept it simple for me. 

[SBMS]

2 minutes ago, Thorfun said:

But can’t cool while the hot water tank is heating, right?

 

I also considered fan coils and floor cooling but it was getting complicated and seemed like a lot of faff. 
 

having separate AC and ASHP just kept it simple for me. 

True but that’s a fraction of runtime really - and can be scheduled in the early hours (when it’s cheap). Personally I think simplicity is having one system doing both, but maybe it’s my OCD not wanting a unit sitting there unused half the year. 

[Nickfromwales]

16 minutes ago, Thorfun said:

But can’t cool while the hot water tank is heating, right?

Usually PV would sort that, or just a midday blast on the immersion heater, direct from the grid, so the cooling can just plod on in the background.

[Andeh]

You can always run the pipework for AC, and first fix it.... Then in future years install the expensive bits either end. Could do it all for a few £100... 

 

MVHR is too invasive and there is no retrofitting. 

[Nestor]

3 hours ago, Nickfromwales said:

Are you cooling the GF slab with the ASHP?

I guess you intend to retro-fit the downstairs ones if you deem that necessary?

I did try cooling the slab with the ASHP but the family discipline closing windows and doors during the hot periods was iffy so gave up.

On sunny days the UVC is 67c with the immersion / PV diverter by 10am.

The lower ground floor bedrooms are north and east facing with smaller windows so not an issue.

The first floor bedrooms with vaulted ceilings are the warmest and AC is just so effective and the running cost offset by PV (+FIT).

 

 

 

 

[Thorfun]

58 minutes ago, Nickfromwales said:

Usually PV would sort that, or just a midday blast on the immersion heater, direct from the grid, so the cooling can just plod on in the background.

I didn’t install a solar diverter for our PV as I figured I’d get a better COP from the ASHP than a 1:1 using a diverter. The ASHP is also run from the PV anyway so, in theory, I believe I’m using less PV to get the tank heated. 

[Nickfromwales]

31 minutes ago, Thorfun said:

I didn’t install a solar diverter for our PV as I figured I’d get a better COP from the ASHP than a 1:1 using a diverter. The ASHP is also run from the PV anyway so, in theory, I believe I’m using less PV to get the tank heated. 

You, sir, are correct. I now routinely dissuade anyone from 'diverting' excess PV as these days it's either going into a battery or they're getting paid for the less complex method of selling and buying back. KISS at its finest.

 

Hoooooooooooooooooooooooooooooooowever....... I would like to interject.

 

In terms of promoting longevity for ones ASHP, I suggest that my clients use the ASHP at dawn, and again at dusk for recharging the DHW, and only topping up at midday off the grid, via the immersion, if it is at all necessary. I dislike the idea of having the ASHP jump from a relaxed state of cooling to a panic state of DHW recharging, and the subsequent downturn in COP.

 

I like to look holistically at how the M&E is presented at the design and concept stage, but furthermore, how long the homeowner will have a reliable system that doesn't need replacement prior to it delivering a ROI. Most ASHP's don't come with a warranty longer than 7 years, which is pretty crap, gas boilers around 10 max, so anything simple that can stave off a premature replacement of a bit of kit in the multiples of thousands, is a worthwhile pursuit imho. Kicks the beloved BUS grant saving into touch if you need to replace these any sooner than expected.

[Thorfun]

12 minutes ago, Nickfromwales said:

and only topping up at midday off the grid, via the immersion, if it is at all necessary.

If only there was a way to nicely automate this I’d be on it as we currently use the cheap period on Cosy to heat the DHW for evening showers at 1pm (or PV if the sun is shining) using the ASHP. 

[Gus Potter]

For me I can see how folk are going for the MHVR, high end glazing, home automation etc.

 

I do think UFH is a great solution, if kept simple like @JohnMo advocates. 

 

I think lot's of you are not actually being eco friendly at all. I think many are trying to do this as hobby to satisfy your need to appear eco friendly and not looking too deep and forensically about what you are doing.

 

Some just want to play about with tech stuff. Some folk buy sports cars..but they don't kid themsevels on they are something they are not.  Many of you are specing high end glazing that only has at most an 7 -8  year warranty. How do you jusatify that? Some are specing ventilation and home automation that will be redundant in ten years time. 

 

But if you really want to make a contribution then I would love to hear about eco friendly ideas that are going to work for 50  years plus that are easily and cheep to maintain,  by someone else, say a young couple buying you home.

 

I think many should be honest with themselves and just ask are we really being eco friendly or just being liberal twats so we look good. 

 

To make a point here. I have three young Chartered Architects on my books at the moment that have come to me to assist on the design of their own houses. They are all really clever and innovative designers. I'm loving working with them. I bring to the table my experience and say let's do this so we maintain / enhance the value of your house, lets look at the best way we can design for the short term.. so you enjoy realising your design but also make sure you can sell the house for a good price later and make sure some surveyor is not going to devalue if you have introduced some tech stuff that is a liability. 

 

 

Edited 11 hours ago by Gus Potter

[SteamyTea]

5 hours ago, Gus Potter said:

But if you really want to make a contribution then I would love to hear about eco friendly ideas that are going to work for 50  years plus

Smaller windows.

10 hours ago, Nickfromwales said:

10 hours ago, saveasteading said:

Like all those miserable people in the Mediterranean climate. It's OK.

They get it all year round. We don’t

I have lived in the South of France, we survived without AC in August.

A lot of the time it is cloudy there.

 

[FarmerN]

21 hours ago, Indy said:

 The reason is that the living areas and master bedroom are both South/West facing, and we have large vaulted ceilings in the master bedroom which may become quite hot and oppressive as the heat is trapped due to the solar gain. 

 

 

In my opinion , how much glass you have will make a massive difference.

Overheating is not a problem for us with windows, two neighbours with glass walls complain about over heating.

  Any chance of Velux window in vaulted ceiling to let heat out, cool bedroom at night.

We have MVHR and like it, have a friend with hay fever who says it’s always better when staying with us, also bathrooms dry quickly and plant room serves as drying room,

[JohnMo]

9 hours ago, Nickfromwales said:

 

Hoooooooooooooooooooooooooooooooowever....... I would like to interject

I just went one step beyond you, now just do DHW heating via the immersion on a simple immersion timer. Energy used overall not much more than the heat pump. Long pipe runs, slugs of cold water... Big heating session when we have used plenty of hot water, ASHP is definitely cheaper, smaller top up heats immersion is cheaper, overall it balances out.

 

You can also install a super simple system if you wanted. Two pipes to UFH manifold from ASHP and you have heating and cooling sorted.

[saveasteading]

Smaller windows facing the sun, larger windows facing away.

Perhaps skylights for central areas of big properties.

Plenty of insulation and perhaps density facing south.

Masses of roof insulation. Tiles make a huge difference.

Shutters or full height curtains facing south.

Opening windows and the effort to purge excess heat in the evening.

High ceilings where excess heat will rise to.

Discipline (teaching the family)  to close doors to keep heat in or out.

A lobby helps a lot as an airlock 

 

Dressing appropriately.

 

That is easy and natural control.

 

We can all live comfortably between 18 and 26°C, so a/c is an unnecessary luxury in the UK.

 

Perhaps daily habits should change to suit, as practised in other climates.

I.e. we embrace hugge in winter and siesta in summer.., and flexibility at mixed up times.

 

If you must live in T shirts in winter and keep the house airtight in summer and yet have all views available, then that is luxury (decadence?)  not sustainability.

 

We should also assume that mains electricity and fossil fuels  become crazily expensive, and design to suit, and adapt our expectations to suit.

 

In the house as described there will be ufh, ashp, solar, batteries. No aircon. And I'm not convinced on mvhr either... I don't think my model needs it.

 

 

 

 

 

[Oz07]

4 minutes ago, saveasteading said:

Smaller windows facing the sun, larger windows facing away.

Perhaps skylights for central areas of big properties.

Plenty of insulation and perhaps density facing south.

Masses of roof insulation. Tiles make a huge difference.

Shutters or full height curtains facing south.

Opening windows and the effort to purge excess heat in the evening.

High ceilings where excess heat will rise to.

Discipline (teaching the family)  to close doors to keep heat in or out.

A lobby helps a lot as an airlock 

 

Dressing appropriately.

 

That is easy and natural control.

 

We can all live comfortably between 18 and 26°C, so a/c is an unnecessary luxury in the UK.

 

Perhaps daily habits should change to suit, as practised in other climates.

I.e. we embrace hugge in winter and siesta in summer.., and flexibility at mixed up times.

 

If you must live in T shirts in winter and keep the house airtight in summer and yet have all views available, then that is luxury (decadence?)  not sustainability.

 

We should also assume that mains electricity and fossil fuels  become crazily expensive, and design to suit, and adapt our expectations to suit.

 

In the house as described there will be ufh, ashp, solar, batteries. No aircon. And I'm not convinced on mvhr either... I don't think my model needs it.

 

 

 

 

 

God what happened to the future and the age of abundance. I'll deffo be putting aircon in my next place and I dont consider myself extravagant. 

[JohnMo]

49 minutes ago, saveasteading said:

not convinced on mvhr either

But build in Scotland to airtightness better than 3 it's mandatory.

[Dave Jones]

MVHR will never be enough on its own to cool the house. I tried, even spent a large sum on a dedicated and useless MVHR chiller intake.

 

As long as you have UFH AND fancoils in all the upstairs rooms you have free aircon.

 

Windows should be closed as a default with MVHR anyway whoever had an issue with open windows. 

[saveasteading]

Just now, JohnMo said:

mandatory

I'd get 2 air tests. One fully sealed, and another with trickle vents open, and some extractor fans uncovered.

The second one to show 3.1 or thereabouts.

[JohnMo]

52 minutes ago, saveasteading said:

High ceilings where excess heat will rise to.

Discipline (teaching the family)  to close doors to keep heat in or out.

Definitely - vaulted ceiling are great. People seem to think they make a room hot and stuffy or takes loads of energy to heat up. But it all depends on you heat the room. High temp radiators, heat goes to fill the top of room first, so yes it does take a lot energy, air con in heating maybe the same. UFH gives a very even spread of heat, top of a vaulted room is hardly any warmer than anywhere else. Summer solar gain the heat can fill a big void above your heads first.

[JohnMo]

2 minutes ago, saveasteading said:

I'd get 2 air tests. One fully sealed, and another with trickle vents open, and some extractor fans uncovered.

The second one to show 3.1 or thereabouts.

Are you a big building firm massaging the results.

 

I installed MVHR and happy with the fresh air feeling every day. 5 years in shower silicone looks nice and white, so bathroom well ventilated.

[saveasteading]

51 minutes ago, Oz07 said:

God what happened to the future and the age of abundance. 

The future is definitely coming.

The age of abundance? Began 1970 or so and applies to a small proportion of the world populace?

US/Israel showing it could end next week for us lucky enough to have had some of it.

[Dave Jones]

12 hours ago, Thorfun said:

But can’t cool while the hot water tank is heating, right?

 

I also considered fan coils and floor cooling but it was getting complicated and seemed like a lot of faff. 
 

having separate AC and ASHP just kept it simple for me. 

 

worst of both worlds is what you have.

 

solar heats the tank when its hot with pv divert, as usually when its really hot there's loads of sun. by 11am latest our 250L tank is 80C via solar diverter.

 

as a bonus it spins the heat pump for free as well for cooling, at least for us with just under 4kw of pv on the roof.

 

It's like buying an electric car and then a diesel car as well as its a faff charging on a long journey.

 

 

[JohnMo]

4 minutes ago, saveasteading said:

The future is definitely coming.

And it starts tomorrow!