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Topic # 133535 25-Oct-2013 13:15
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Hello!

This is a question for all of you who have experience with ventilation/heating/cooling in reasonably modern homes, built in the last few years with double glazing and modern insulation standards...

We are thinking about building a home in the Auckland area. It's a two story home, open-plan living and kitchen downstairs, bedrooms upstairs. Being a new house, the insulation standards are reasonable. We'll even have somewhat upgraded insulation (more than minimum required by building code) and very well insulating windows.

In your opinion, what is the best combination of ventilation and heating systems for a modern home like this in the Auckland area?

Does such a home even need an extra ventilation system, such as a DVS?

Staying cool in the summer is nice, but it's probably even more important to stay warm in the winter. So, some sort of heating might be required (and possibly air con), even with modern insulation? What are the options here? The building company seems to propose DVS-style ventilation and a normal, wall mounted heat-pump in the open-plan area downstairs.

Is that a good combination? Are there better options for heat? I'm sure there are more energy efficient ones than a heatpump, but they often also are much more costly to install. The builder quotes around $3500 for the ventilation system and $4000 for the heatpump.

Any help, opinions or experiences are greatly appreciated.

Thank you very much!

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  Reply # 921643 25-Oct-2013 13:27
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Thoughts:
- Modern houses still need heating and cooling, and more importantly ventilation because they're so airtight.
- PVC double/triple glazing, not aluminium
- Duct in a system to each room that can feed in air - fresh outside air, warm air, cool air, along with a flexible option for heating and cooling. A whole house heat pump would be awesome. Ideally an electronic or at least a manual way to shut down the air flow to unused rooms, and minimise it to rarely used rooms. Retrofitting to a two storey house is just about impossible, but when it's being built it's trivial.
- DVS units are for ventilation, don't believe when they say they're for heating. They're not.
- Get a good heat recovery ventilation system. From memory http://www.cleanaire.co.nz/ makes a good one, but avoid the big brands like DVS/HRV.
- Consider putting in under floor heating, or central heating.
- Don't do ugly wall mounted heat pumps, that's just stupid, the building company should be ashamed. They're big, ugly, and loud. Duct it in, put it in the ceiling space, and have perhaps a double fan heat exchanger unit outdoors to power it all. If you have wall mounted units you'll probably need three or four.
- Mitsubishi lossenay (may have spelled it wrong) can integrate heating and ventilation.
- You should get an engineer specialising in this stuff to design it for you, including automation. $20K perhaps, but you'll have a home that's super comfortable all year around.

Also:
- Cat6 everywhere
- Lots of storage
- Patch/media cupboards.
- Put ducts everywhere to get from ceiling to wherever you might want things - more ethernet cables, TV cables, aerials, etc




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  Reply # 921646 25-Oct-2013 13:32
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Read this site, even if you don't go with the brand it explains it quite well.




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  Reply # 921649 25-Oct-2013 13:36
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Interesting. I am building a similar house in auckland also. We will be opening windows for ventilation as we always have done. And one biggish heat pump for the almost all open plan downstairs. My parents in law's new house around the corner is similar sized, double glazed with no heat pump and barely needed a heat pump though they only koved in newr the end of winter. We will put one in for the colder nights it is needed, plus potentially cooling though again prefer the use if windows and cieling fan in master bedroom

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  Reply # 921653 25-Oct-2013 13:40
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Retrofitting you end up with a big ugly heat pump hanging on a wall, often in a pain in the butt place. Planning your heating and ventilation in advance you can do a much better job. Of course cutting holes in the ceiling for ventilation impacts insulation.

Ventilation systems are also more secure than leaving windows open, though my PVC windows have very strong two point locks so I leave them open any time I feel like it.




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  Reply # 921790 25-Oct-2013 17:07
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Im buikding from scratch not retrofitting.

Hrv and similar products are a con. People need fresh air and in particulat let the high amount of VOCs in the first new years exit the house rather than push it around to breathe them in again. Going for high solar gain in the west to trap heat and only put carpet upstiars in bedrooms despite carpet being the unhealthy product that it really is (hard not to carpet bedrooms). my wifes health obsessed and were both paleo living naturally as possible so will leave supposed heat recovery systems alone amd use the money for thi gs that provide benefits we consider a higher priority. On the heating side id love to go subterrean but the cost is outrageous if u dont have acreage (or a large pond). Will go a heat pump this house and think harder about subterranean and how I can do this myself next time around when I dont have jennian or similar standard building company building my home. Ive seen a guy using his piles and long driveway on grand designs which worked, all designed by himself.

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  Reply # 921794 25-Oct-2013 17:20
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What do you think ventilation products do? Move air around inside the house?

A good ventilation system takes fresh air from outside the house, warms it (in winter) by passing it through a heat exchanger that pulls the heat from the stale air coming from the inside of the house, then puts the warmed fresh air inside. In winter it cools air rather than heats. It's set up to draw the stale air out and putting fresh air in places that need it - eg it pushes fresh air into bedrooms and lounge, and extracts it through a central point like a hallway. This reduces condensation, though double glazing is also required to eliminate it really.

Non heat-recovery products just push cold air in, they can be bad for heating efficiency.




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  Reply # 921799 25-Oct-2013 17:41
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A true heat recovery system will but not an hrv or similar system, like I said. They shoukdnt be allowed to call it an hrv. Either way these are not necessary in the climate I am in. Fresh air is hard to beat and free. My current 250 sq m house doubke glazed with windows open all year round and single heat pump is very comfortable indeed, and this next house better design to harness the sun will be even better, even without subterrean plus heat exchangers

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  Reply # 921888 25-Oct-2013 21:19
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Passive Houses purport to reduce running costs significantly. www.phinz.org.nz

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  Reply # 921892 25-Oct-2013 21:41
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For a two story house with a large open plan area a high wall air conditioner will perform really well. Ducted units aren't suitable for this application as you don't generally have space for the ducting in the intermediate floor.

Ducted units with on/off dampers are a mixed bag for multiple zones (i.e. one unit feeding 4 bedrooms and maybe a lounge upstairs) . If all the zones have the same load and all the ducts are the same size the perform OK, if you have different loads, which is much more common, you end up with one zone being just right and all the others either too hot or too cold. You can't put modulating dampers in either as you are using dampers which isn't really controllable, they are designed for zone isolation only.

If you do decide to go for a ducted option make sure you consider how you are going to service and/or replace the indoor unit in the future. If you get 10 years out of a domestic heat pump you are doing well so you need to consider this.

It really comes down to your budget, you can spend whatever you like really.

If you just want heating, and have reticulated gas, radiators can be very cost effective. You can use a gas boiler or calorifier (i.e. like a Rheem Infinity) to produce both your home heating and you domestic hot water. This sharing of plant can lower your install cost and reticulated natural gas is very cost effective (in the same ballpark to run as heat pumps) and radiators are a really nice form of heat, you can even get them for bath rooms that double as heated towel rails. Something like this type of system.

http://www.waterware.co.nz/products/central-heating/comfort-plus

If you don't have reticulated gas, don't bother bottled gas is very expensive.

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  Reply # 921896 25-Oct-2013 21:47
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Central heating's common in most cold countries (NZ is a cold county). It's just common sense really, and is really effective.




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  Reply # 921908 25-Oct-2013 23:28
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NZ is a cold country? Perhaps it depends on where u live but auckland and north if doesnt appear to be. Ive lived in netherlands, england, sweden, spain and the very north of usa, 4 of which got cold. Aucklands winter just gone was nothing. My tenants didnt even get through a cubic metre of firewood i left them and i used a heat pump for maximum of 3 weeks in total. And the world is only getting warmer

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  Reply # 921913 26-Oct-2013 00:30
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The first thing you need to do is pick what energy sources to use for hot water and heating. To do that you need to figure out your expected usage. A single heatpump and electric hot water cylinder, should be fine if your house will be a small 2 bedroom, for just yourself. If your house will instead be 6 bedroom 300+m2, for 8 people. That single heatpump and electric cylinder won't cut it. Natural gas would be far cheaper.

Also do you want a woodburner or not?

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  Reply # 921917 26-Oct-2013 06:50
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BrowneAction: NZ is a cold country? Perhaps it depends on where u live but auckland and north if doesnt appear to be. Ive lived in netherlands, england, sweden, spain and the very north of usa, 4 of which got cold. Aucklands winter just gone was nothing. My tenants didnt even get through a cubic metre of firewood i left them and i used a heat pump for maximum of 3 weeks in total. And the world is only getting warmer


Yes, most of NZ is a cold country. I have an old house in Wellington, but it's well insulated, I have two heat pumps running as required for around 6 months a year. There's a law about to go through parliament to enforce heating and insulation in rental properties. Down south it's even more important. Modern houses built with good insulation giving thought to passive energy will need a lot less heating than older houses.




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  Reply # 921920 26-Oct-2013 07:44
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if u can get reticulated gas, then ducted gas heating is just as economic as a heatpump, and solves your heating AND ventilation needs

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  Reply # 921922 26-Oct-2013 08:05
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Worth noting that DVS and HRV are brands, like Holden and Ford. They are commonly positive pressure ventilation systems, the science being that increasing the pressure inside the house with less humidity reduces the humidity within the house.

The brands may or may not also sell balanced pressure ventilation systems. These suck air from inside and outside, swap the heat for the humidity, and push air into the house and outside.

The second option is much better, but more expensive as it doesn't push heat out of the house with humidity, and uses outside air rather than roofspace air.

Jon

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