Double Glaze / Old windows

Forums › Home Workshop DIY › Double Glaze / Old windows

1 | 2 | 3

20574 posts

Uber Geek

Trusted

Lifetime subscriber

#1571522 14-Jun-2016 10:54

chimera:

It will retain the heat longer - assuming that all the other obvious insulation areas are covered (roof, floor, minimising drafts etc)

It should make a big difference, not only does the double glazing in itself help with heat retention, but the reduction of condensation will greatly take the cold sting out of the air. If you are having a cold night, go and run a dehumidifier overnight (wouldn't do regularly, expensive to run) and see how much more comfortable it makes your house (when the air is drier)

Weigh up the pro's and con's yourself... if you're staying there for a while, its well worth doing. If you're going to sell in the next couple years, well maybe just invest in a heat pump instead.

https://www.energywise.govt.nz/at-home/windows/double-glazing/

Yes it will retain heat longer, but above it says "I'd rather get double glazing and floor insulation etc. etc. then have people using heaters" - I just think the expectations are higher than what will happen.

I've insulated my house slowly over time. First I put wool in the ceiling, big win for temperature. Next I put in a heat pump to the lounge, bedroom area, which was awesome. Then I did underfloor insulation and a ground sheet, which was a big win for smell in the house and virtually no change in temperature. Then I did wall insulation, foam pumped in, which again made no real difference. Next I put in more ceiling insulation, which was a big win and made the house feel a lot warmer. Then I did the older retrofit double glazing, which reduced condensation and made the house feel slightly warmer. Next I removed a freestanding fireplace from the kitchen, which was a huge win as the room was then properly insulated and sealed - before that wind whistled in from the ceiling cavity as the roof can't touch the hot chimney. Next I moved the heat pump to the kitchen and put an even bigger unit into the lounge, which was a win for the kitchen / dining area. Next I did the proper double glazing, which has made a small difference over the old retrofit double glazing in the living areas, but I can't tell if it made the kitchen area feel warmer, however it has reduced condensation.

So my experience is:

Ceiling insulation makes a big difference you can feel
Removing fireplaces so the ceiling can be sealed is a big win
Adding a heat pump is a huge win, so long as you have ceiling insulation
Every other step is small and incremental that I couldn't really feel. It probably reduces the power bill a bit is all. This of course depends on the house.

Willuknight

146 posts

Master Geek

Trusted

#1571525 14-Jun-2016 10:56

I'm probably going to be in this house minimum 10years, not planning on moving any time soon.

The house currently has a non working airflow system that takes heat from the lounge with the woodburner and vents to all the bedrooms. I think all I need to do is replace the main unit to use that. Even if I can't get that system back up, my idea with the double glazing is that once you heat up your room, the room will retain heat, so rather than leaving a heater on, you can warm up the room and it will stay nice for the rest of the evening. It's definately already better than my old house in that once you're in bed and it's warmed up, you don't freeze to death.

My current plan is:

1) Take care of heat loss

- double glazing
- floor insulation
- 2nd blanket on roof insulation

2) fix DVS

Willuknight

146 posts

Master Geek

Trusted

#1571526 14-Jun-2016 10:58

I figured I'd tackle the windows first as they seemed to be the areas of the biggest heatloss?

timmmay

20574 posts

Uber Geek

Trusted

Lifetime subscriber

#1571534 14-Jun-2016 11:07

Willuknight:

I'm probably going to be in this house minimum 10years, not planning on moving any time soon.

The house currently has a non working airflow system that takes heat from the lounge with the woodburner and vents to all the bedrooms. I think all I need to do is replace the main unit to use that. Even if I can't get that system back up, my idea with the double glazing is that once you heat up your room, the room will retain heat, so rather than leaving a heater on, you can warm up the room and it will stay nice for the rest of the evening. It's definately already better than my old house in that once you're in bed and it's warmed up, you don't freeze to death.

My current plan is:

1) Take care of heat loss

- double glazing
- floor insulation
- 2nd blanket on roof insulation

2) fix DVS

I still think your expectations are waaay too high for double glazing. Double glazing may reduce heat loss by 10%, but most of the heat goes out the ceiling. If you have a single layer of batts putting in a second layer would be a cheaper, bigger win, than double glazing IMHO.

Regardless of what you do a house doesn't heat up and stay heated up. If a room is 15 degrees and you heat the air up to 23 degrees when you get home from the work then everything else in the room (furniture, walls, carpet) has to be heated up as well, which effectively takes heat from the air, cooling it. So over the evening things will all heat up, requiring heat input the whole time. Of course insulation simply reduces heat loss, it doesn't eliminate it, so houses will cool down as it's colder outside. Windy days can be worse because it increases the rate of heat being removed, and also if the house isn't sealed it will directly cool the room.

So for $6K you will reduce your heating bill a bit, and if your windows don't seal it might be a big win, but the $6K will never pay for itself financially. It might pay if you ever sell the house, and with the slightly increased comfort it might be worth it. I decided it was worth doing, but partly to reduce maintenance, partly because windows didn't seal properly, partly because windows wouldn't open properly and some were painted over, etc.

Willuknight

146 posts

Master Geek

Trusted

#1571540 14-Jun-2016 11:20

Thanks for the really awesome feedback.

I guess my main concern isn't making it pay for itself through power savings but by increasing comfort. My windows currently are completely sealed and I don't even get 'crying' windows, so maybe I should rethink where I can target my money to greater return.

It sounds like my top priority should be putting in another ceiling blanket. Do you know if underfloor insulation helps floors feel any warmer? I feel like when I walk around on carpet wearing socks that the floors are zapping heat from me.

timmmay

20574 posts

Uber Geek

Trusted

Lifetime subscriber

#1571549 14-Jun-2016 11:26

If your windows aren't getting moisture on them I wonder if you have too much airflow, or if it's too cold inside. The only time I've not had that is when it's double glazed or when a ventilation system is pumping cold air into the house.

I don't feel like underfloor insulation made the floor feel a lot warmer in my house. As heat rises you'll always find floors are colder. I just wear slippers. The under floor heating in the bathroom is nice, but is essential with tiles otherwise even in summer they feel like they're about at freezing point.

More ceiling insulation should make a difference you can feel immediately. Double glazing might increase comfort slightly, and if you sit/sleep under windows you'd notice the reduced chimney effect of cold air falling off the windows.

chimera

506 posts

Ultimate Geek

#1571551 14-Jun-2016 11:27

Clearly the biggest gain will be a heat pump. It's entire purpose is to generate heat - everything else discussed are simply insulators and there purpose is to retain heat/minimise heat loss - its not an apples vs apples comparison - an appliance that generates heat will outweigh anything else you do to any area of the house. I'm simply discussing the insulating side of the equation.

All I can say is your mileage will vary. It will totally be dependent on the house YOU are insulating.

For example, timmmay says little difference felt heat wise when doing underfloor insulation - on the contrary, a noticeable difference was felt when we did ours (as under one portion of our house is exposed to drafts) It may have only been +1 degree, but that was enough to notice a difference. Likewise with the double glazing, he says it will make minimal difference however in our case (perhaps moreso due to the location of the windows and position of our house being exposed) it made a big difference.

If you want instant warmth right now because your house is really cold, then spend your money on a heat pump. If you are reasonably comfortable at present and want to take a slight cold sting off the air, then plan for insulation.

Perhaps best to speak to the professionals who can assess your house based on its current state.

Equinox IT

Cloud spending continues to surge globally, but most organisations haven’t made the changes necessary to maximise the value and cost-efficiency benefits of their cloud investments. Download the whitepaper From Overspend to Advantage now.

chimera

506 posts

Ultimate Geek

#1571555 14-Jun-2016 11:32

Also if you do underfloor insulation, use the polyester / pink batt stuff - don't use expol (IMO) its hopeless.

We did a rental we have that has wooden floors and the difference on underfloor insulation (I stapled polyester - cocoon i think the brand) underneath, the difference was significant

Again, it really depends on YOUR house

timmmay

20574 posts

Uber Geek

Trusted

Lifetime subscriber

#1571558 14-Jun-2016 11:36

Yeah if you have care wooden floors you might notice a big difference with underfloor insulation. We had 12mm thick foam padding, then thick carpet, so we effectively had 24mm of insulation already. Adding another 4 inches of rigid polyester insulation made little difference, but a ground sheet made a huge difference as the ground under the house was damp.

More insulation then a heat pump is where I'd suggest you look. If you can do a ducted heat pump combined with a ventilation system that could be a big win. Mitsubishi lossnay is one system, not sure how good it is. Alternately any wall mounted heat pump with a good heat recovery ventilation system, but the heat pump has to be sized for the house not the room. Note that HRV and other branded ventilation system providers are expensive, I like the look of a Chch based Cleanaire.

Jaxson

8041 posts

Uber Geek

Trusted

#1571593 14-Jun-2016 12:35

Just to chip in with some basics, lets talk quickly about condensation.

Basically that's caused by warm air being able to hold more moisture than cold air. If you take a can out of the fridge, lets say of red bull as I'm not drinking alcohol this month, on a cold winters night when your house is shut up and the heaters are going. If you put the can on your table, within 5 minutes it will have condensation running down it. This is because the surface is cold and when the air around it cools, the air can't hold as much water vapour as when it was warm, and it's forced to dump some of the water it was holding out. This condensing of water back to a liquid is called condensation, and it occurs on cold surfaces that take heat away from the air, and reduce it's ability to retain the water it was holding.

So, to remove condensation on windows, you can heat your windows, which is essentially how double glazing 'reduces condensation'. The air gap between the two panes of glass warms up to a temperature half way between the inside temperature and the outside temperature. The inside glass pane stays warmer than it would be with single glazing, and therefore it doesn't cool the air inside as much as it would do with only single glazing, and because of that you don't end up with as much condensation on the inside window.

Now another alternative is to remove the moisture from the air with either:
Ventilation (replacing some of the heavily moisture laden air with fresher air from outside with less moisture in it) which can get tricky when it's 2 degrees outside.

Dehumidification (removing moisture from the air by passing it over cold coils and collecting it when it drips off the bottom). Some heat pumps advertise this feature, but it can only occur when you are passing air over cold coils, so this wont occur by simply running a heat pump in heating mode over winter. If the unit has a dehumidification mode, then this will periodically cool the air to dehumidify it a bit, and then switch back to heating to restore the warm temperature it just actively cooled to dehumidify.

Remove the moisture at the source. This can mean everything from ensuring you use overhead range hoods when boiling food, drying clothes in the garage/outside, using bathroom extraction fans, ensure surface water is removed from your section and directed away from the house itself, and moisture barriers are used to separate the house from the damp earth etc.

Of note in all of this, is that whilst double glazing will reduce your window condensation, it won't reduce your moisture content. This is an important factor because water can absorb a lot of energy before it heats up. That's why it's good to throw on (some) fires, as it will absorb a lot of the energy on offer and cool it down quickly. For the home owner, this means that it's far cheaper to heat the air in your house if the air does not contain a lot of moisture. If it does, then you'll be throwing a lot more money into heating that same volume of air than you would be if could remove some of it.

Double glazing is a form of insulation, in that it slows heat transfer out through your windows. Potentially so too does a top pelmet and some floor to ceiling heavy curtains. Insulation simply slows the loss of energy that you've paid to put into your home. A heat pump is a high cost to purchase/install but low cost to run fan heater that adds energy into your home, or takes it away in summer/dehumidification mode.

Which brings me back to where timmmay left off. Manage your expectations around exactly what the addition of any home improvement step is going to achieve and deliver. I think I mentioned sound right back at the start of this thread. That may be a genuine consideration for double glazing, but if it's solely to save money, then one needs to really consider the outlay to returns, and determine if you could achieve the same result (or a better result) another way also. I'd be quite clear about what my requirements/drivers and expectations were, and then re confirm that double glazing will deliver those.

timmmay

20574 posts

Uber Geek

Trusted

Lifetime subscriber

#1571610 14-Jun-2016 12:52

I manage moisture by running a fresh air ventilation system during the day, which reduces moisture, makes it smell better, and reduces the energy required to heat it. I don't run it all night, but I do have it come on for two 15 minute periods after dinner is cooked then mid evening. I accept that some moisture will build up at night, because we have double glazing the impact is minimal, and it's all blown out the next day anyway. This system works well for us, but if we had a big family we'd probably run ventilation more.

1eStar

1604 posts

Uber Geek

#1571618 14-Jun-2016 13:08

Most DVS systems are a bit of a scam. They blow COLD air in to give you the impression your windows aren't crying moisture. If people spent that coin on insulation and heating they'd be far better off. If you want a ventilation system, try opening the windows from time to time.

chimera

506 posts

Ultimate Geek

#1571638 14-Jun-2016 13:24

1eStar: Most DVS systems are a bit of a scam. They blow COLD air in to give you the impression your windows aren't crying moisture. If people spent that coin on insulation and heating they'd be far better off. If you want a ventilation system, try opening the windows from time to time.

Totally agree. I got an HRV. It actually is great for ventilation - but only at certain times of the day. Later at night when you're trying to warm the house by some alternate means, the HRV is blowing typically cool air from the ceiling around the house. Completely counter intuitive. What it needs is a heat pump/aircond unit on the HRV intake for winter/summer use. Just using ceiling cavity air (which is sucked in from outside) is a total waste of time, its either too cold in winter or too hot in summer. I'm graphing all this information at present to determine the optimal heating solution for my own home (including searching aliexpress for heat exchange units that may work with the HRV!)

Oriphix

523 posts

Ultimate Geek

#1571639 14-Jun-2016 13:27

Willuknight:

What are people's thoughts on retrofitting? I have a big house with lots of big single glazed aluminium windows. Roof and walls are insulated. None of the windows have the boxes above the curtains to prevent air seeping in and non of the curtains are floor length.

I've been quoted $6000 to do all the bedroom and living area windows, seems like the best thing to spend money on as windows will be my biggest heat loss?

Can you give me the company you used for a quote?

I was also exploring this option.

Oriphix

523 posts

Ultimate Geek

#1571642 14-Jun-2016 13:38

timmmay:

Yes it will retain heat longer, but above it says "I'd rather get double glazing and floor insulation etc. etc. then have people using heaters" - I just think the expectations are higher than what will happen.

I've insulated my house slowly over time. First I put wool in the ceiling, big win for temperature. Next I put in a heat pump to the lounge, bedroom area, which was awesome. Then I did underfloor insulation and a ground sheet, which was a big win for smell in the house and virtually no change in temperature. Then I did wall insulation, foam pumped in, which again made no real difference. Next I put in more ceiling insulation, which was a big win and made the house feel a lot warmer. Then I did the older retrofit double glazing, which reduced condensation and made the house feel slightly warmer. Next I removed a freestanding fireplace from the kitchen, which was a huge win as the room was then properly insulated and sealed - before that wind whistled in from the ceiling cavity as the roof can't touch the hot chimney. Next I moved the heat pump to the kitchen and put an even bigger unit into the lounge, which was a win for the kitchen / dining area. Next I did the proper double glazing, which has made a small difference over the old retrofit double glazing in the living areas, but I can't tell if it made the kitchen area feel warmer, however it has reduced condensation.

So my experience is:

Ceiling insulation makes a big difference you can feel
Removing fireplaces so the ceiling can be sealed is a big win
Adding a heat pump is a huge win, so long as you have ceiling insulation
Every other step is small and incremental that I couldn't really feel. It probably reduces the power bill a bit is all. This of course depends on the house.

This is awesome. I might give that a go.

The main reason I was looking at double glazing is our house windows gets fully wet (the whole house). We have only recently bought the house in it about 6 months.

Didn't notice anything till it started to get cold. It does have bats in the roof but I guess we can put another layer it won't cost that much.

But I guess retro fitting the windows might be a cheaper alternative if you didn't notice double glazing did that much difference.

We don't have a heating solution for the house currently which we need to think about as well.

1 | 2 | 3