nz housing is on the slippery slope of failure.

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#3357553 26-Mar-2025 16:59

gzt:

Handle9: How much heat do you think an extract rangehood actually removes from the space? It’s not a lot at all.

Lots and lots. An externally vented rangehood removes tons of heat. Essential in summer.

My rangehood externally vents in normal circumstances. There was a problem. I noticed the house was getting stupidly hot with the rangehood on. Later I noticed air was blowing out of it near the ceiling. On removing the cover I found no retainer was fitted to the motor/hose during installation and the vent hose was now detached from the motor. The unit was blowing all the heat out at ceiling level. Fixed the hose retainer. House temperature problem solved.

As a bonus in summer we run the rangehood when the oven is in use. It is surprisingly effective at keeping internal temperatures down by removing a proportion of the hot air generated by the oven and venting that externally.

While your anecdote is nice it really doesn't prove all that much.

The amount of heat removed by a range hood is really limited - it's essentially waste convective heat. Most of the heat from the cooker is transmitted into the cookware. From there it's radiated heat which a rangehood does nothing to solve.

A rangehood removes waste air which has some energy but not significant amounts of heat in the context of other heat sources. It's not nothing but it's far from significant compared to the other elements.

I've worked in HVAC control for the best part of 20 years and never seen a rangehood used as a temperature control device because that is not what it's purpose is. It's used for the control of fumes and humidity.

gzt

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#3357644 27-Mar-2025 07:25

Handle9: The amount of heat removed by a range hood is really limited - it's essentially waste convective heat. Most of the heat from the cooker is transmitted into the cookware. From there it's radiated heat which a rangehood does nothing to solve.

The amount of heat removed by a rangehood with an effective exhaust including 'waste convective heat' is significant for the comfort of the occupants. Rather than offer additional anecdotal evidence obtained by placing my hand in front of the external vent while not cooking and cooking, I will use an analogy we can both agree shows effective cooling of radiated heat with airflow. CPU heatsinks emit radiated heat. Without a fan a CPU heatsink becomes hotter. CPUs are always fan cooled. A CPU and exhaust fan illustrates heat removal by advection sometimes called forced convection. We can now agree the CPU and exhaust fan removes radiated heat. Sure, a case housing provides advantages in airflow management. The CPU fan remains effective even without a case.

In a similar way the rangehood causes air movement across multiple radiative heat sources and then exhausts that heat externally. This includes temperature reduction of nearby objects which have absorbed radiated heat like the splashback. You have already agreed that hot moist water laden energy dense air typically generated by cooking is effectively evacuated by a rangehood. Without exhaust the heat and moisture is going to make occupants uncomfortable.

Your main objection has been and will be that these effects are insignificant. I maintain that all these effects in total are significant for the comfort of the occupants.

gzt

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#3357648 27-Mar-2025 07:43

neb: Is it "specified with" or [snip]

Imo the logic is applied after kitchen design. Ye Olde row style/vertical apartment housing typically placed the kitchen and cooking area on an external wall. Coincidently with the kitchen area looking into a small yard and a back door. I'm not suggesting an unthinking return to that. Newer design trends typically use a ranchslider for external access sometimes with deck. This requires that the kitchen is placed on an internal wall. External wall design = specify rangehood exhaust. Internal wall design = specify rangehood recirculating. Job done.

tweake

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#3368314 28-Apr-2025 15:38

looks like its all go

‘Trusted’ builders to certify their own work "Trusted builders and tradespeople will be able to sign off their own work, in the latest initiative from the Government to speed up house building."

copying the building hell thats in aussie at the moment. i would avoid those builders like the plague.

mattwnz

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#3368317 28-Apr-2025 15:43

Considering how many defects council officers pick up on new builds, and they don't pick them all up either, it may not end well for some home buyers. I wonder if banks will require prepurchase building inspections on new builds before lending as a result of this.

SomeoneSomewhere

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#3368323 28-Apr-2025 15:52

It's bad enough trusting sparkies to self-certify and we can at least get prosecuted for safety faults. General carpentry is a wild west.

tweake

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#3371389 8-May-2025 11:32

Ventilation rules to be revamped as a vain attempt to band aid bad house designs.

Ventilation rules to be revamped to ease plight of Auckland townhouse occupants

Building and Construction Minister Chris Penk says the government is planning to increase ventilation requirements in new homes, to address the problem of sweltering townhouses.

more nz building idiocy. typical nz building industry making houses worse because they can't be bothered designing houses properly, because there is no rule limiting solar gain. a simple legal mistake that can easily be fixed.

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richms

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#3371439 8-May-2025 11:56

They also need to add max temperature into the healthy homes thing for rentals. Ventilation doesn't solve it. Aircon does.

Richard rich.ms

gzt

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#3371525 8-May-2025 16:58

That is a long article. "[Penk] said the short answer was "Yes". The long answer is as long as the article and maybe longer. The current headline:

"Ventilation rules to be revamped to ease plight of Auckland townhouse occupants"

does not relate to any of the current article content. As richms says, it implies healthy rentals. That may or may not be included in the minister's short answer. There is nothing about it in the article.

mattwnz

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#3371559 8-May-2025 20:07

tweake:

Ventilation rules to be revamped as a vain attempt to band aid bad house designs.

Ventilation rules to be revamped to ease plight of Auckland townhouse occupants

Building and Construction Minister Chris Penk says the government is planning to increase ventilation requirements in new homes, to address the problem of sweltering townhouses.

more nz building idiocy. typical nz building industry making houses worse because they can't be bothered designing houses properly, because there is no rule limiting solar gain. a simple legal mistake that can easily be fixed.

Solar shading/roof overhangs over large windows is what should occur. But it can affect how the building looks and probably most importantly to developers, the amount of land needed for a dwelling, while keeping it within the setbacks

tweake

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#3371564 8-May-2025 20:20

mattwnz:

Solar shading/roof overhangs over large windows is what should occur. But it can affect how the building looks and probably most importantly to developers, the amount of land needed for a dwelling, while keeping it within the setbacks

you pretty much said it, its overhangs/shading vers looks and large windows.

its not just developers but clients. there is no legal reason to push back against what the clients want is the big issue. if someone designs a perfectly fine house thats cool in summer, the client will take their business to someone else who will design a hot house that the client will complain about being to hot or simply sell off and make it a problem for someone else.

Handle9

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#3371567 8-May-2025 21:15

tweake:

its not just developers but clients. there is no legal reason to push back against what the clients want is the big issue.

You mean the people who own the house get to decide what is important to them? Outrageous!

SomeoneSomewhere

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#3371573 8-May-2025 23:01

Putting quality and safety restrictions on what buyers want is basically the entire purpose of the building code, including the efficiency obligations.

tweake

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#3371606 9-May-2025 09:12

Handle9:

tweake:

its not just developers but clients. there is no legal reason to push back against what the clients want is the big issue.

You mean the people who own the house get to decide what is important to them? Outrageous!

as above, this is why we have a building code. clients don't know and often don't care. eg they want a hot house and then complain its hot. the other problem then becomes that they just added another bad house into nz housing stock so future buyers only have bad houses to choose from. a house effects a lot of people over the decades. so its not just about what the client wants but whats suitable for all the other people that will be in that house over the next 50-100 years.

my fav example is the high end house that won building industry awards. it has huge huge amounts of windows. the best the industry can do and its quickly sold off. all the subsequent houses of that design all had timber battens across the windows to shade them. no prize for guessing why the original award winning master piece got sold off.

Bung

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#3371613 9-May-2025 09:31

The Wellington city council will learn about solar gain in the building they are moving into. When Telecom occupied it as "Britannic House" it had great harbour views but if the blinds weren't drawn by 9am you were in for a hot day on the Jervois Quay side of the building.

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