Designing of a thai bio-climatic roof (paper)

I just came across this paper and thought the concept to be interesting, but not sure how it works...

Author(s)

WAEWSAK J. ; HIRUNLABH J. ; KHEDARI J.

Affiliation(s)

Energy Technology Division, School of Energy and Materials, King Mongkut's University of Technology Thonburi, Bangkok, 10140, THAILANDE

Abstract

This paper presents an innovative roof design. The roof is designed in response to the Tropical climate of Thailand with respect to human thermal comfort. It is composed of a combination of CPAC Monier concrete and transparent tiles on the outer side, air gap and another combination of gypsum with aluminum foil board and translucent sheets on the house side. It has two functions in operation: In daytime the roof acts as a solar chimney and induces natural ventilation. The transparent tile provides not only sufficient daylight for housing but also help in increasing the ventilation rate. In nighttime, the Thai bio-climatic roof plays the role of a roof radiator to dissipate the heat accumulated during daytime by long-wave radiation to the sky dome. The roof surface temperature decreases below ambient in several degree celcius. The cool air located between the two sides of roof flows downward providing nocturnal cooling.

Monopitch roof football center under construction

Near the turn-off for Bang Bua Tong on Phuttamonthon Rd. West of Bangkok. (I would have gotten more varied shots, but was getting suspicious looks after sneaking through the gate.)

A church built for the cost of a motorcycle, Chiang Mai

Designed by the pastor, who also bought all the materials and acted as contractor.

Roofs (Thai Architecture Elements Series)

These little books are published to make available unused images from Nithi Stapitanonda's book Architecture of Thailand (2006.) In each he focuses on one or two architectural elements with images and some text, this one is divided by roof type. I'd like to get copies of "Surfaces" and "Colors." There are also volumes entitled "Stairs & Railings," "Statuary," and "Gates & Fences." (Update: See also Doors & Windows, Surfaces, and Colors.)


Some notes from the text regarding pattern recognition:

Tiered roofs
-visually reduce the mass of a large-scale building, making it look slimmer and more buoant
-reflect the status of the building: more tiers=higher significance of building, owner, or dwellers
-high, vertical layering implies faith in Buddhism or the King

Single-planed
-in the North, where it is cooler, eaves reach down to cover the windows. "Ka Lae" are crossed pieces of wood at teh gable-top to give good fortune, and "Ka Ko" are carved pieces covering the end of purlins.
-in the Southern region with heavy rains and winds, houses on stilts are not as high as those in Central and Northern Thailand, and have a higher pitch to facilitate drainage
-Northeastern style roofs are of the lowest pitch due to dry climate & low rainfall

Multi-tiered (like wedding cake-cone form, spire)
-based on belief related to the mythical Sumeru Mountain...highest rank of roof.

Gable & Hipped
-enable good rainwater drainage and air ventilation
-builders prefer to use small roof tiles on high pitch roof planes
-tiles placed so as to make a border on each roof plane help to make the roof appear light and buoyant

Roof Elements
-Cho Fa, gable-top decoration made in bird-beak shape or fish-lip shape
-Khrueang Lamyong, gable eaves & tile end covers
-Hang Hong, gable end decorations made in the shape of Nage heads placed in a row
-Thais consider it inappropriate to decorate common buildings to be as or more elaborate than temples and palaces.

monopitch sketchups

The slopes are noted in the drawings....the 1:10 creates some lofty ceilings, and may not be conducive to multiple activities happening in the same space noise-wise, if the mezzanine is left open. Using a tiered roof (below) helps define the spaces below better. I'm not sure about cleaning the clerestories...but it seems that most Thais wouldn't be too daunted by getting up on the roof.
This 1:4 pitch allows similar definition of space, but with a single roof.
The 1:2.4 pitch similarly defines the space, and gives more headroom in the mezzanine without the ceiling elsewhere becoming too high. It may give too much sun-exposure on the high side.
I like the dynamic look of this one, and how it uses the roof to create interest. It also allows the steep roof to sit further down on the structure.

some roofs

These are from last week, and I'll be working on exploring a monopitch roof with mezzanine as well.

I also added a better picture of that building on campus with the cascading flowers here.

10 degree roof shadow studies; winter solstice @ 4pm

There is about a 1m eave on all of these.

Roof Images cont'd

Here's another example of a recent linear raised ridge vent roof.



And a stepped pyramid roof on an old farm building near Chiang Rai.

roof images

I was out on the elevated highways yesterday, the perfect height for observing the tops of buildings---and snapped some quick photos of roofs. Here are a bunch of multi-level roofs which seem to help with making it look less like a warehouse. (although it doesn't look like any of them are actually using the architecture for ventilation, sadly.) The pitch seems pretty steep. Another thing I've seen a lot, and I'm not sure what the actual construction is, is where the shingles/roofing sheets are bounded by a concrete ledge at the ridge and intersections that gives it a more finished look---and also a ton of added weight, I'm sure. The example below isn't the best, but you can kind of see what I am talking about at the far left hand corner of the green roof.We passed this temple under construction, which I thought was so interesting:

Sheet roof materials

Check out Corroshield Kool at www.mahaphant.com

They do asbestos free profiled roofing sheeting in 3 colours with some interesting cladding options, including profiled louvres that can be used for side ventilation and diffused daylighting; also vented ridges, ventilation 'rollers', translucent lighting sheets and other accessories.

An alternative is Onduline, a French product made under license in Penang- not sure whether this is sold in TH.

This seems an appropriate technology for CTS, but how to avoid it all looking like a factory/warehouse?

David

Alternative Roof Forms for large Thai buildings

Hi Valerie,
Thanks so much for the solar model studies. I think this whole question of an appropriate roof form is going to be a major challenge for us. Here are some preliminary thoughts:
LOWER PITCHED ROOFS
- not very Thai, but are there precedents?
- lighter loads on the structure per m2
- shorter columns
- greater wind uplift
- greater risk of leaks
HIGHER PITCHED ROOFS
- more Thai, greater 'presence'
- scope for attics/mezzanine floors within roof space
- High walls or windows under high roof eaves (in gable walls, or high walls under mono-pitch roofs), adding cost and maintenance issues, but enabling better high level ventilation and daylight.
- Greater overhang and/or sun screens required on north side (assuming this is the higher
side in a mono-pitched structure) to protect facade from direct sunlight
- larger cross-walls required, with greater cost, need for piers or other stiffening
ISSUES FOR ALL ROOFS
- design of roof eaves on high and low sides of monopitch roofs to reduce wind turbulence and encourage cross ventilation.
- what is the optimum pitch of a monopitch roof to encourage cross-ventilation? This will need to take account of different conditions at different times of day and year. How is the 'stack effect' of such a roof reduced by thermal insulation in the roof? Maybe it's important to distinguish between quilt insulation and foil insulation (ie reduce UV transmission
rather than conducted heat).
-how is cross-ventilation effected by the width of a building, relative size of windward and leeward ventilation openings etc?
-How many of these variables can be tested by computer modelling?

FLICKR finds: roof...what makes it Thai?

1. thai building, 2. Thai Building, 3. thai building, 4. Thai Building, Chiang Mai, 5. Thai Building, 6. 4-73 BK_ thai building, 7. Traditional Thai-Style Building, 8. Local Thai Hotel...built on the river, 9. Nonthaburi - Thai House 1, 10. Suan Pakkad Palace museum - main building, 11. Thai house, 12. Traditional Thai Architecture, 13. Thai Style Architecture, 14. Ban Thai resort, 15. Uthani Thai River Lake Resort

What makes a roof look "Thai?"

Possibilities:
-Color! (preferably brown)
-the roof's plastic sheet-like-nature--a large expanse coming down to meet the ground
-multi-level, with changes in slope
-eave props
-large overhangs
-decoration