A little knowledge can be "Dangerous"

"A little knowledge can be Dangerous".. it is a bit of an overstatement, but serves to drive home a good point.

Some cases encountered looking back:
1) Another example of "Didn't do it right first time"
A friend visited my BH before building his. He implement too the concept of pre-humidified the air between double walls. I visited his BH after some months into operation.. guess what?

Water sprinkled onto inner walls! All internal walls were soaking wet to the point nesting planks became moldy. Humidity > 95%!

2) Case of "solving a problem while creating another down the road"
Tweeter sound level deterioration - Solved by a new parallel link all the way back to amplifier. It works.. but unwittingly spun a spider web. Over time, you'll loose track which is what.. from here to where! So what is the root cause?

Worst if a wiring cross over mistake that "shorts" the output instead. It won't blow the amps immediately, but overheats it to failure gradually. Fancy trace wiring inside a dark BH? Better rewire all over again.

3) Case of "Taking a Panadol to cure headache ignoring the cause"
Whenever I came across use of exhaust fans (other than hanging sun screens) to cool the BH. That is like taking a Panadol. Sure it works by flushing out excess thermal energy.. but what is the root of the problem?

4) Case of "I know how" attitude, don't bother "if I don't understand"
Think this is the worst kind - problem is in the head too, not just in the bird house!

Some time back, I read in another blog someone labeled my "stupid logic" as I put in lay term "more humid air" rises.

If only one cares to understand deeper, water vapor being gaseous state of H2O, is lighter in molecular weight than Oxygen, O2, & Nitrogen forming the bulk of atmosphere.

In my application described... the humidifier was placed at bottom of staircase to serve 2 floors. Water vapor being lighter will drift upwards naturally to increase moisture content of upper level.

So the "I know how" attitude was quote:
"Hi v.... i have seen his blog and i think he is explaining with a stupid logic . More humid air is lighter than less humid air . I think i won't believe it . I have solved the room temperature myself and i call it an experience. " as proudly declared.

What was the relevance of its citation? Pretty amusing!

That alone tells how much the underlying issues being understood.

Everything that works, I need to understand how on a scientific basis. I rest my case.

A "Leaky Thermos Flask" bird house design

Prior to building the bird house, I did a fair amount of homework. There are more than 10 iterations and reviews. Fortunate to know someone who think alike to share and brain storm together. Yes, we have different opinions but the outcome of 2 heads was definitely better than one.

Let me cite a case of poor thermal design to begin with - seen in Krabi, Southern Thailand. Installation of plastic sun screen was an after-thought in fixing a problem recognized after months of operation. Evidently it is still not a solution as it cannot withstand weather forces over time. There are so many similar cases seen everywhere.















Before going further may I share this paradigm "Quality is doing it right first time" from Philip B. Crosby, a father of quality philosophy with a zeal for zero defects. The picture above speaks otherwise!

Of all the bird houses I've seen in S.E. Asia, except in northern part of Thailand, nowhere employs double-wall design. No mention of it's use in any literature I browsed at the time. The idea is nothing new in building industry. Perhaps it's the perception of higher building cost in people's mindset. If one fix a budget and focus primarily on costs, the builders wouldn't encourage it either even if they knew better. Why should they if it eats into their bottom line profit? Else that is a good reason to up the cost. But does it really cost much more?

If single wall designs are egg shell in comparison to massive walls of limestone caverns. Double-wall design is one step up from the design perspective.

I like to compare that to the Thermos Flask because it is the best case of economical thermal design. The whole bird house is conceptualized with a thermal mass model - the walls, internal airspace and everything else within.

Light color walls & roof provide some degree of radiation heat reflection similar to the silver reflection lining of the flask. The vacuum space is ideal in blocking thermal conduction. Next best of course is to replace by "cost free" airspace.




















It is not uncommon to use double-brick walls to increase the thermal mass as well as for added security of a stronger wall. So cost of adding airspace in between is not significant.











In colder climate, construction practice even filled space between walls with insulation materials.












How good is the insulation property of air space?
We all know Styrofoam is a low cost insulating material and widely used. A comparison can be insightful. This is also an example a little maths provides more depth in understanding.

Recently a certain "consultant's blog" featured a new building with Styrofoam embedded inside walls. Did I remember correctly also photo of a bird house wrapped externally with Styrofoam "skin" (posted years ago) labeled as "creative"! (Forgot the weather resistant factor? Amateurs can be ignorant, not Professionals)

Perhaps those approaches may need some rethinking after review of following numbers.

Relevant thermal property to consider are:
Thermal conductivity of Styrofoam, k(Styrofoam) = 0.033 W/m.K
Thermal conductivity of still air, k(air) = 0.024 W/m.K
Lower values means less conductive and hence better insulation property.

Units of k are W/m.K where
W is rate of energy flow (heat) in Watts (or Joules/sec) across 1m^2 surface.
m is 1 meter material thickness
K is temperature in deg. Kelvin, analogous to deg. C for practical understanding.

N.B. Total thermal energy (Joules) transfer across 1m material thickness over a period, t (sec),
is to multiply k, by surface area(m^2) x t(sec) x T(deg. K)
where T is temperature difference across surfaces at 1m apart.

Taking the ratio of 0.033/0.024 = 1.375
It simply means that "still air" is more effective than Styrofoam insulation by 37.5%. Surprise?
Or the use 10cm thick airspace is equivalent to 13.75 cm Styrofoam! So the final choice depends on economics of building methods in use.

Conversely, the air space within my double walls is 90 cm wide (enough for staircase). Multiplication of 90x1.375 = 123.75 cm; that is the equivalent of "Styrofoam filled space". See the comparative advantage trapped airspace.

So a little basic science and maths give much clarity - no rocket science as you can see, only a matter of practical engineering considerations.

In my bird house, a matrix of air-holes punctuated the walls designed to provide a combination of both "Stack" and "Cross" ventilation. With the air-flows at entrance holes the bird house design simply becomes a "Leaky Thermos Flask". The effectiveness of air space insulation should be derated due to air movements through vents.

As often cited in literature, best to orientate the bird house along "east-west" direction to reduce foot print to sun's heat. I have a long wall facing south-west. It don't bother me, for that is a solar wall receiving thermal energy to create humidity; by sprinkling water to the wall from inside. Humidified air gets into the bird house as part of air change.

Few more examples of maths and physics application:
1) Simple trigonometry calculation to know the effective surface area, normal to west, receiving sun's heat.

2) Calculations of the energy needs at various rate of air exchange while maintaining constant humidity within.

3) Use of water as a thermal reservoir inside the bird house.

With in-depth understanding, one can design to limit and control amount of energy inflow during the day with an acceptable daily temperature cycle, regardless of building orientation. Fluctuations of energy flows due to external and uncontrollable factors that affects temperature and humidity stability with air change is a matter of balancing with extra energy input with electronic controls.

In essence that's my concept of a minimal energy bird house. Think I did enough work on bird house designs, with depths more than I've read in books and forums.

Siting of bird house

Choice of location undoubtedly is more important than design of bird house. For any specie to propagate its population, fundamental to it are availability of food sources and safe sanctuary to bring up the young.

In context of swiftlet farming, most would consider locations in close vicinity to an existing bird house nucleus. Land and property prices escalate rapidly once an area is established. Capitals pouring into new buildings usually out pace the natural growth rate of the bird population.

Pak Phanang, probably the most establish nucleus in southern Thailand. No other place I've been to that the 'bird nest' buildings are so blatantly displayed. All large buildings here are bird houses, huge 7 storey are common! Unless you are an early bird or with loads of cash, entry barrier here is formidable.












The next best locations are along flight paths where birds go in search of food, especially the return path in late afternoons. So one must really do some homework in this regard. If birds have feeding range of 50KM (as commonly cited), then it make sense to survey an area within 50KM radius from establish nucleus. It is best to check out first on Google Earth for a bird's eye view of the entire area, followed by field trips to sample birds in feeding grounds.

A relatively new nucleus (mark in red box) further north along the Thai coast. Even here land prices rose dramatically in recent years. Note the close proximity of feeding grounds and rivers. Birds have to feed afar as it is insufficient here to support a large population.












If you know the feeding grounds well, there is no need to even consider flight paths. As in my case, the bird house is sited within feeding grounds and 15KM and 30KM from two established nucleus; just 300m away from an established bird house.

IMHO, this is a better approach. I avoid paying high premium on land cost and birds can feed late into evening hours. I did consider initial growth rate may not match those new bird houses right in the nucleus, but so far it is not yet proven.

A New Book on Bird House Designs

I am glad to have a small network of friends in information sharing. Come to know of a new book by Drs. Arief Budiman.. price is pretty stiff though at Rp 2,500,000 (US$232)!

Interesting to know if there are new concepts in there.



















Guess I'll do a review after a read on it.

What else about bird house designs?

There are several authoritative books on bird house designs. Not a general subject to dwelt with here. Just that a chain of thoughts that lead from one topic to another.

Last year I had the privilege to visit a friend's bird houses in Malaysia. These are very successful ones, all over a thousand nests each. I had enough time immersed in each internal ambiance and note any details that caught my attention.

They engaged a consultant initially. The results were pretty mediocre. So they took upon themselves and improved from there. At the end of the day I posed a simple question to his father, "What is the most important factor in your opinion?" He paused a moment and summed up with a thoughtful answer, "It's the design."














The three words don't tell much, but the answers are profound within. A good point as food for thought in spare moments. I did ponder over many factors.. reviewed variations of bird houses visited, think through critically and sieve out those more important than others.

This is a full row of bird houses, all look the same externally. The differentiation factors are inside - the "know how".















A point to highlight is that micro-environment though important is an essential factor but not the most crucial to the success of a bird house. In case anybody may be mislead from my last blog.

As a final note, suffice to say literature and seminar materials I came across cover general concepts in design but not much in depth. Good to write a treatise on it some day.

It's all about ENERGY

This word hit me as I followed how cyclone Yasi unfold itself. The weatherman described it as an "energy system moving across...". That's a very concise description and a "massive energy system" indeed.





It also reminds me of the time when I studied bird house designs. In essence we are trying to emulate a cave environment - its temperature & humidity stability. Natural caves are in massive limestone hills that insulate it from external environmental fluctuations. Constant water sip-page helps to maintain high humidity within. Air exchange through cave entrances/openings maintain oxygen supply to sustain life. Dark cavities offer safe sanctuary from predators. Swiftlets must have its echolocation capability develop and evolved over tens (hundreds?) of thousand years.















In the case of bird house, the walls are egg shell in comparison. Climatic changes have direct impact to its micro-environment. It is common knowledge daily cycle of sun's heat has direct influence, the dominant factor in fact. If one observes the daily temperature cycle inside a bird house, it typically peaks around 4-5pm and coolest around 4-5am.

In a nutshell, it is the movements of thermal energy in/out of the bird house in daily and seasonal cycles. The thermal insulation properties of the building materials are basic to design considerations. First thing I did was to dust off my old physics book for a refresher on thermodynamics. Understanding heat and thermal energy is fundamental.















So it is all about thermal energy in every aspect of bird house micro-environment design. I have a mental picture of an underlying thermal model when taking each design consideration; may it be orientation, humidity, air-exchange etc. They are all inter-related.

In depth understanding of this subject would certainly help to improve one's bird houses to the next level.

Harvest Trolley Test Drive & Cyclone Yasi

What has Cyclone Yasi got to do with my Harvest Trolley test drive?

Well, as I was testing the new motor drive yesterday, this mega storm was heading land fall by midnight (Australian EST). Expected to be the largest cyclone to hit Australia in living memory. Naturally it interest me.











I had difficulty uploading the test drive clip to YouTube all night. For some unknown reason, it kept failing over umpteen attempts! In between I followed the event live on ABC (Australian Broadcast Corp) on internet.










Ground zero was Mission Beach, some 50 Km south of the town Innisfail.















This was where I skydived 5 years ago with my daughters. It brought back memory of us packed like sardines as the plane climbed to 14,000 ft. I can't imagine the courage needed to take the leap. It was not necessary - I was simply pushed out soon as I hung my legs out the plane's door! Dropping like a stone on a 10,000 ft. free fall before the parachute opened at 4,000 ft.















This is Mission Beach where we landed. I survived and the feeling was GREAT!













The upload was successful eventually this morning.



It has 6 control directions: forward, reverse, forward & reverse right turn; forward & reverse left turn. We are pretty satisfied and can proceed to final build.

As for the aftermath of Cyclone Yasi, it is very fortunate no reports of fatality thus far. Queenslanders had braced themselves very well!

But there were wide spread devastations - this Mission Beach home with only toilet left standing!