Landed: Aircon Planning

[wersingaporeans 0]

Hi all, wondering how do u decide what type of aircons to install and how many split units on each floor?

In my previous place, I have tried to install 28k btu for system 1 but I don't find the higher btu has any difference 

Can't seem to find this information (or maybe landed owners leave this mostly to their architect) 

Do you go by 1 condenser per floor or?

Appreciate if any masters can comment on it

 

Level	Ceiling Height			Aircon type	Estimated Total BTU	BTU/hr	Build sqft	Cooling capacity (kW)	Build m2
Level 1	Kitchen 2.65 metre Living Double Volume 5.7metres	Dry Kitchen Living room	18k btu each?	Dry Kitchen 1 Split Living 1 Cassette	36,000	127,053	2,002	37.2372	186.186
Level Mezzanine	~2.35 Metres	1 room	14k btu each?	1 Split	14,000	53,817	848	15.7728	78.864
Level 2	~2.55 Metres	4 bedroom	8-9k btu each?	4 Split	32,000	106,428	1,677	31.1922	155.961
Level Attic	~2.75 Metres	2 bedroom	12k btu each?	2 Split	24,000	81,868	1,290	23.994	119.97

 

Edited March 28, 2022 by wersingaporeans

[snoozee 98]

don't combine your floor area when calculating aircon cooling requirements. break them down into individual rooms.

a guide to calculate the BTU is to take the total area in square meter, divide by 5 and then multiply by 3412 to get the BTU.

eg: 20sqm room will require 20/5 x 3412 = 13648 btu. so you can get an aircon with wall unit which can provide at least 13K btu

going by the above calculation, your mezzanine room of 848sqf will be about 80sqm which gives you at least 54k btu required. so your plan of one 14k btu unit is hardly enough.

I note that you have a double volume living room and you plan to have a ceiling cassette aircon installed. Are you planning to have the ceiling cassette installed in the double volume space or at another area where the ceiling height is lower? Assuming your floor to the floor of the upper storey slab is 5.7m, after deducting the slab thickness of about 20cm and your drop of false ceiling of another 40cm so you can install the ceiling cassette aircon, your aircon will be about 5m high. how are you planning to do the maintenance? This means your aircon contractor will need to bring in scaffolding in to access the aircon every time maintenance is needed and this will cost you a bomb. you will be better off installing wall mounted units or ducted aircon which comes out from the side of the wall instead. Also your floor area is huge at 186sqm. going by above calculation, the required BTU is about 127K which would need about 3 condensers.

assuming your 2nd storey bedrooms are all same sized, each room will be about 39sqm which will mean about 26kbtu of cooling is needed for each room.

your attic's rooms assuming each is 60sqm, this will give you 41k btu of cooling required.

So if you look at the above BTU requirements, you are likely to require single split aircon units for each room since multi split units cannot get the required amount of BTU required to cool down the rooms properly. Assuming you install 3 condensers for your living room and dry kitchen and then 1 condenser for each room, you are looking at having 11 condensers for your house. have you catered for enough space for 10 condensers? Do also note that some condensers which are for higher BTUs are huge and are more than 1m in height. You need to think of how you can also remove the condensers in future if they break down and needs replacement.

I would suggest you rework your spreadsheet to break down the floor areas into individual rooms instead of going by the absolute built up area. Once you remove the irrelevant areas like stairs, corridors and toilets, I think you will be left with smaller floor areas and your required cooling requirements will also go down and that would be a more accurate representation. If the numbers come down enough, you might be able to get away by using multi split units for the rooms instead of single split units.

If you are getting quotes yourself, send your floor plans to the aircon suppliers and have them work out a proposal for you.

Edited March 29, 2022 by snoozee

[wersingaporeans 0]

12 hours ago, snoozee said:

I note that you have a double volume living room and you plan to have a ceiling cassette aircon installed. Are you planning to have the ceiling cassette installed in the double volume space or at another area where the ceiling height is lower? Assuming your floor to the floor of the upper storey slab is 5.7m, after deducting the slab thickness of about 20cm and your drop of false ceiling of another 40cm so you can install the ceiling cassette aircon, your aircon will be about 5m high. how are you planning to do the maintenance? This means your aircon contractor will need to bring in scaffolding in to access the aircon every time maintenance is needed and this will cost you a bomb. you will be better off installing wall mounted units or ducted aircon which comes out from the side of the wall instead.

Thank you so much snoozee for the insights. I was looking through videos of double volume houses and notice most of them use the ceiling cassette. I was also wondering how to maintain the aircon!! 

how do these owners clean their aircon hur????

 

I will ask my builder to help calculate the floor area for each room to have an accurate calculation! 

Edited March 29, 2022 by wersingaporeans

[yoongf 11]

Hmm.. based on your lvl 1 floorplate of abt 2k sqft, your land plot shd be quite big.. ie this is quite an atas house.

But... all your ceiling heights are unusually low, lower than HDB substantially. Are u sure you want to proceed with this design? 

Low ceiling heights feel much hotter, and for the attic floor which is your master rm, will require substantially bigger cooling power. Also rooms that gets the afternoon sun. 

For me.. i agar at 70btu per sqft to be able to get that instant freeze feeling.

 

 

[snoozee 98]

don't believe what is mentioned in the videos. 6m or 7m high ceiling is exaggerated. comparing the scale of the items in the house, I would say the first house has a ceiling height of just over 5m (instead of 6m) where the 2nd house has a ceiling height of less than 5m (not 7m)

anyway if you don't use the aircon that often, you don't need to service it too often as well. Maybe the owners just do major servicing every 6 months and of cos need to pay for scaffolding la. Anyway the first house boss owns a reno company as well so maybe can easily get his workers to bring in scaffolding as and when is needed so not a big problem. 

[snoozee 98]

12 minutes ago, yoongf said:

Hmm.. based on your lvl 1 floorplate of abt 2k sqft, your land plot shd be quite big.. ie this is quite an atas house.

But... all your ceiling heights are unusually low, lower than HDB substantially. Are u sure you want to proceed with this design? 

Low ceiling heights feel much hotter, and for the attic floor which is your master rm, will require substantially bigger cooling power. Also rooms that gets the afternoon sun. 

For me.. i agar at 70btu per sqft to be able to get that instant freeze feeling.

 

 

haha. i didn't pick up on the ceiling height. mezzanine ceiling height 2.35m cannot pass BCA requirements also.

[wersingaporeans 0]

the land size is 2000 sqft inter terrace, those figures are all indicative for rough planning. The height should be around hdb ceiling as we wanted to have more rooms for multi generation living. 

for double volume living room, ducted aircon was suggested but I personally don't know any landed home owners with ducting aircon. 

my friend who rebuilt his semi d installed a lot of split aircon units instead. I am more inclined to use all split unit aircons after snoozee point about the additional scaffolding cost. 

After reading up on google, seems like split aircon is easier and cheaper to maintain ! 

[snoozee 98]

26 minutes ago, wersingaporeans said:

the land size is 2000 sqft inter terrace, those figures are all indicative for rough planning. The height should be around hdb ceiling as we wanted to have more rooms for multi generation living. 

for double volume living room, ducted aircon was suggested but I personally don't know any landed home owners with ducting aircon. 

my friend who rebuilt his semi d installed a lot of split aircon units instead. I am more inclined to use all split unit aircons after snoozee point about the additional scaffolding cost. 

After reading up on google, seems like split aircon is easier and cheaper to maintain ! 

I would suggest you work with your builder to redesign the height for each level. As mentioned, BCA requires a minimum of 2.4m finished floor to ceiling height for any rooms so your 2.35m for mezzanine will not pass TOP inspection.

a 2.5 storey house can be built up to 12m in height. with your 5.7m plus 2.55m plus 2.75m, you have a total of 11m. add in 20cm for each floor slab (mezzanine, 2nd storey and attic) will be 11.6m. If your roof thickness is less than 40cm, you can actually allocate height to the 2nd storey. 

Also if you are planning to do false ceilings to hide the beams and such, you will lose more height as well. The problem with low ceiling is that heat gets trapped within the rooms. For your inter-terrace, you have no side windows as well to allow for the heat to escape unless you are going to do set back on the sides to carve out space for side windows. Another potential issue with low ceilings is that if you plan to install ceiling fans, the low height will become a bit dangerous. a DC ceiling fan will have an overall height of about 35cm. So if your ceiling is only at 2.4m, it means the fan will be only about 2m from the floor and can easily be touched when an adult raise the arm upwards. If you have small kids, they may jump off the bed and hit the fan as well which is very dangerous.

While it looks and feels grand to have a double volume ceiling, you also need to think of the practical aspects of living in the rooms upstairs with such low ceilings. If i'm not wrong, newer flats are now designed with floor to ceiling of about 2.6m so your 2.55m is actually lower. The 2 videos you shown are houses which are in 3 storey zones so they have more height to play around with to create such high double volume ceilings. Unfortunately you don't have that additional 3.5m in height to play around with for your house in a 2 storey zone.

If you can, reduce the height of your 1st storey by a bit and add that to the 2nd storey instead.

Just to share, my house is also in a 2.5 storey zone and it is also designed with a mezzanine. the floor to floor levels split are 2.8m (1st to mezzanine), 2,7m (mezzanine to 2nd), 3m (2nd to attic), 3.5m (attic to roof). But my architect done a good job with  space planning and allowing for drops for certain areas on the 1st storey so the result is that that one doesn't feel the low height levels. I also have a double volume ceiling is is about 5m high. I installed ducted aircon as I don't want to have the wall mounted split units exposed.

Anyway, if your land size is about 2000 sqf, there is no way you can get such a big build up area (1677) for your 2nd storey. Assuming your land dimensions are 20ft wide by 100ft deep to give you 2000sqf, this will translate to a dimension of 6.096m wide by 30.48m deep. URA standard setback for landed houses is 7.5m front and 2m back. So with this setback in mind, your house foot print can only have a max of 6.096m wide by 20.98m deep which gives an area of 127.89sqm or 1376.6sqf. Of cos I'm calculating based on standard planning norms so if your house is in an area with slightly different planning criteria then my calculation will be wrong. But the main thing is that you need to check with your builder on the exact dimensions of each room you want to have aircon in so you can do the planning correctly. Else you will be wasting money in over-sizing the aircon requirements than what is really required.