[JJ7]

Now that tall residentail towers are becoming normal, can someone confirm how say above 15-20 storeys in height, that extract ventilation from bathrooms and kitchens is achieved and also supply ventilation to habitable rooms.

Is it by vertical supply and extract shafts with communal fans and subsidary unit fans or grilles directly on the facade/balcony soffit or set behind the cladding with secondary grilles to the void?

How is the positive and neagtive pressure to the facades at heights above 15-20 storeys dealt with? - bigger fans or just non return flaps?

Are trickle vents to habitable rooms still used with adaption?

Fans in the UK are limited to efficiency compliance, thus making vertical shafts very large to incorporate.

Any help greatly appreciated.

[natelox]

These sound like questions for a mechanical engineer. I have limited knowledge in the field and thus will try to answer as best I can.

Bathroom/kitchen ventilation is achieved just as in any home: through duct work and to the outside of the building. In Vancouver (I would have assumed this was common with all construction, but I recently found out it is not the case), the duct work is run through the slab. It is considered good practice to have the exhaust vent under the balcony above to prevent water ingress.

http://farm1.static.flickr.com/45/420238715_bac4e18e40_b.jpg
You can see them here. Looks like poor design to me, as wind driven rain could easily enter the duct work.

Ventilation is typically done by pressurizing the corridor and allowing air to enter the units with either continuous fans or by use of the kitchen or bathroom fans (which would reduce the pressure in the unit and draw ventilation air indoors). This method has two major advantages. Firstly, odours are controlled as they cannot enter the pressurized corridor. For the same reason, it also aids in fire protection (smoke cannot enter the corridor or elevator shaft or stairwell).

Pressure is likely controlled on each floor with dampers (something akin to a variable air volume system). I haven't heard of any problems with excess pressure. Most buildings lose air at 0.5 ACH passively. I have seen a few interesting pictures of distorted curtain wall glazing due to pressure, but nothing more than minor aesthetic issues.

http://farm1.static.flickr.com/47/115177785_d52a11666d_b.jpg
You can see the distortion in the reflections of an adjacent building. Some appear as though they are bubbling out while others are flat or being sucked in.

[mthd]

what building is the second photo?

[MayDay]

You might want to do a search on my magazine's web site: http://www.hpac.com/, or HVAC Talk, an affiliated forum http://www.hvac-talk.com/vbb/

[SFUVancouver]

The second building is called the Carina and it is at the foot of Jervis street in Vancouver's Coal Harbour neighbourhood. It's one of my favourite in the city. Its curtain walls gently bulge out on both sides and was designed to be reminiscent of a ship's sail.

[brian_b]

The second building is called the Carina and it is at the foot of Jervis street in Vancouver's Coal Harbour neighbourhood. It's one of my favourite in the city. Its curtain walls gently bulge out on both sides and was designed to be reminiscent of a ship's sail.

I really like that first building. Maybe it's just the perspective, but I love it.

[bryson662001]

My 60's era highrise uses tunnels in the ceiling slabs running from each exaust fan to the outside. There is one of these for each kitchen and bathroom. The aluminum caps with doors that open when the fan is turned on were just installed a few years ago. Before that each vent was just an open hole. (The windows are new also)

http://i85.photobucket.com/albums/k50/bryson662001/IMG_0678.jpg

[superchan7]

I think in cities with large-scale high-rise residential developments the plumbing is heavily centralized into a main unit for the entire structure. There are always pump rooms and machinery rooms on mechanical floors or the roof.

I'm inclined to this hypothesis because I never see vents on the sides of the apartment buildings in Hong Kong. Either they're centralized or they're very cleverly hidden away.

Somebody correct me if I'm wrong.

[bosmausasky]

I am no expert but one reason you do not see the vents on the side of some building is because you may have a intake or exhaust fan near the ground level 2nd or 3rd floor that supplies/exhausts air from lets say floors 1-15. Then on the roof you would have fans that supply/exhaust for floor 16- 30.