Calculate energy for polycarbonate roof, different U-value

[A.S]

Hello!

I am about to build a conservatory, 29 sqm in the Gothenburg area.

I don't intend to have the conservatory "winterized," but with the option for frost prevention and heating for events or when extra space is needed. I will insulate the floor joists well and the "autumn-plus" wall sections. Everything from Willab Garden.

Now to the question:
I have compared 32mm and 40mm, the difference is only between U-values of 1.1 and 1.0. That is, quite little...
But the price for just the roof is + 6800 SEK.
That is, quite a few kWh if one were to buy more electricity for the money instead of a better insulation value.

I have calculated a few different scenarios as follows:
U-value * temperature difference * area = power loss.

What is striking is that even if I were to heat the conservatory all year round to ~20 degrees, it would take many years before one reaches 6800 SEK, i.e., "recoup" the cost of the more expensive roof. (14 years)

Am I thinking correctly?

 

[Fred vom Jupiter]

Keep in mind that thicker roofs steal more light while being stronger.
I'm thinking along the same lines as you and am leaning towards the thinner roof.
I'm also considering installing a solar panel that blows in warm air, also to get ventilation for the conservatory.
https://www.clasohlson.com/se/Solventilator-Sunwind-AirPlus-100/p/Pr368016000

 

[Anderscurl]

We have a "winterized" patio with 32mm multiwall polycarbonate. It is practically used as living space year-round. The same temperature in the patio as the rest of the house, 19°. I measured the temperature of various building parts on Tuesday for fun since I received an IR thermometer in the mail then. The inside of the multiwall polycarbonate maintained almost the same temperature as the ceiling in the living room of our villa from '65. The temperature was measured at 18.8° in the living room ceiling and 18.0° in the patio ceiling. The outside temperature was +2-3°.

 

[A.S]

Thank you,

I've also reflected on the fact that thicker roofs = darker, which we don't want as it will make the room inside the conservatory darker.

Additionally, Willab Garden has something they call IQ reflex, which in practice sounds very good on a hot summer day... at the same time, I'm thinking of a day in April or May when the solar load is high but the temperature outside is low, then you WANT the warmth from the sun. Then it’s called "IQ" and sounds smart... but... ahem...

I will probably go for a 32mm roof, but still interested if I've calculated correctly.

 

[surris]

Hi!

I'm about to build a conservatory, 29sqm in the Gothenburg area.

I don't intend to have the conservatory "winterized," but still with the option to keep it frost-free and heat it up for occasional parties or when extra space is needed.
I will insulate the floor joists well and use "autumn-plus" wall sections. Everything from Willab Garden.

Now to the question:
I have compared 32mm and 40mm, the difference is only between U-value 1.1 and 1.0. That is, quite little…
But the price for just the roof is + 6800kr.
That is, quite a lot of kWh if you were to buy more electricity for the money instead of better insulation value.

Calculated a few different scenarios as follows:
u-value * delta.temperature * area = power loss.

What's striking is that even if I were to heat the conservatory year-round to ~20 degrees, it would take many, many years before reaching 6800kr, i.e., "calculating home" the more expensive roof. (14 years)

Am I thinking correctly?

You are thinking absolutely correctly!

 

[boihus123]

How did it turn out, is it along the same lines, did it work well with 32 mm?
Do they let light through well?

 

[A.S]

How did it go, along the same lines, did it turn out well with 32 mm?
Do they let through light well?

Hi,
It turned out well!

They let through a "reasonable" amount of light, I don't feel blinded in bright sun and it's definitely not too dark in winter.

As for insulation capacity, my observation is that no matter how good the roof or glass is, there is more cold draught around all joints and tracks than I assumed.

So I would say be satisfied with 32mm.

 

[boihus123]

Hello,
It turned out well!

Lets in "lagom" amount of light, I don't feel dazzled in blazing sun and not too dark in winter.

As for insulation capability, my observation is that regardless of how good the roof or glass is, there's more cold draft around all joints and tracks than I assumed.

So I'd say go for the 32mm.

Thanks for the response.
Another thing, how is it with condensation? In my previous patio, I experienced air condensing against the roof (I had regular single plastic then), and it dripped a lot, possibly also due to a lack of ventilation in that space, but is this something you experience?

 

[A.S]

Thanks for the response.
Another thing, how is it with condensation? I experienced in a previous patio that air condensed on the ceiling (I had then regular single plastic) and it dripped a lot, maybe also due to lack of ventilation in that sunroom, but is this something you experience?

No problem. That shouldn't be able to happen if you have some form of insulated type of channel plastic.
Steam/warm air condenses on cold surfaces.