Check out this ebook on the conditions required in your house to create condensation and therefore mould.

Conditions of a healthy home.
Come back and tell me your thoughts and if you find it useful tell your friends to come and grab a copy.

How to stop condensation and mold

Click the image below to download the pdf 
It is quite surprising reading.
How to stop condensation and mold
download your copy here

Houses with no roof cavity are the hardest to ventilate, they can feel very cold even though the thermometer says it is 21 deg C. These are the homes that really need to be ventilated heated and insulated well.

Ventilating a home with no roof cavity, a flat roof or a skillion roof design is something that should be planned prior to building and should involve a ventilation specialist and the architect who both understand each others point of view and the needs of the client.

There are only two ways to remove moisture from any container (ie your home)
Firstly : the easiest is to get a dry air source – drier than the inside of your home and blow it in, which in turn pushes the dampness out
and dries the container.
The only air source you have is the outside air but it is unfiltered, cold and sometimes equally as damp as your home.
To use this source you need to be very vigilant as to when you open and close your windows and or doors.
If you work away from your home, the problem is you are not at home to make the changes when need be,
If you leave your windows open as we did for many years, your home is no longer as secure.

Secondly: The expensive way, like a kettle, we remove the water (moisture) by heating it up and the water is boiled away and the kettle becomes very dry.
When we heat our homes in NZ we only heat them for 3 to 6 hours a day (depending on where you are) for 4 to 6 mths of the year, unlike England,
Europe or Canada where they heat for 24 hours a day for 8 to 10 mths of the year, and in those places they effectively dry the house out by heating
out the water, yes they have some different ventilation systems but you need somewhere to ‘hide’ or put it (usually in the ceiling).

A home with no roof cavity is very hard to ‘ventilate correctly’ to give you fresh but drier air than what is either inside or outside your home in all seasons.

If you have a space under your floor which can access each room in the house, then I would suggest you investigate a ducted central heating system which will circulate and heat the air in your home but at times can bring in air from outside which can be heated and filtered.
Therefore introducing dryer air in your home and reducing the possibility of condensation.

It is becoming very important that home designers, architect’s and the like, are very aware of the needs of all homes in relationship to Heating, ventilation and insulation as all 3 are equally important as each other and a balance is required in each home, along with using as much free energy as is available at the site of the proposed home.

In answer to the above question….
This can also be used as a guide as to the basics of choosing a ventilation system for any home, without a central heating system installed.
#1. It needs to be vented into each of your bedrooms and all living spaces.
#2. When the roof cavity is warmer than the house it should be capable of moving up to 2 1/2 to 3 times the air volume of your home. (so with a higher stud it is important the system can cope with the volume of your home)
#3. The system you install should work around your needs, if you want a heat transfer (say you have a large w/fire in your lounge) you can have one.
#4. I’m guessing your home does not get tooo hot in summer, Therefore you probably don’t need a summer fresh air supply, but you should be able to add that process if you need to.
#5. You should be able to choose the target temperature in your home – that way the system is working to raise or lower the house temperature to your needs, and should not cut off when the roof gets hot but the house is not up to your chosen temperature.
I hope this helps if you need more specific info email me through the contact page.

Humidex – This helps to explain the feeling of Cold and Hot in relationship to humidity and dampness in your home

Check out this chart on humidex and humidity and temperature

Discussion points on the EECA Home ventilation document

The Report done for the EECA in January 2009

I will be commenting and explaining each of these points over the next few weeks.


The Need for Ventilation to maintain indoor air quality

The New Zealand Situations

Principles of Positive Pressure ventilation systems

Moisture control, airflows and ventilation

Is the roof space a good source of ventilation air?

Summary of Positive Pressure ventilation systems


Principles of balanced pressure ventilation systems

Further explanation of the Heat Recovery and the Energy Recovery Ventilation systems – There is a very important difference.

Heat Exchange Ventilation in purposely built new homes

– possibly low energy homes

and then the

The EECA had a report done (Jan 2009) on the home ventilation systems available in New Zealand.

This report (like most reports) seems to be done from a perspective and reading other reports. Some of the writer’s points of view are valid but still need discussing. 

Over the next few weeks I will put my perspective across to allow open discussion on various sides of this debate and I welcome any comments on my points of view.

Have a look at http://www.easierventilation.co.nz/eeca-home-ventilation-systems-assessment.html which is where i’ve started, if you have any questions or specific points you would like me to cover please leave a comment below this blog or  email me here .

Looking forward to opening up the areas of misunderstanding.

13 Jul, 2009

Heat pumps and Condensation

Posted by: charles In: Ventilation and Heat Pumps

Almost every day I get called into homes that have heat pumps installed and are still getting large quantities of condensation on all windows throughout the home.
These clients have been told by the heat pump sales person that installing a heatpump, they will remove all condensation. Yes a heat pump (AKA airconditioner) can remove moisture from the room which it has been installed but this can only happen efficently in cooling mode and below 20 deg C, in other words summer.
They have tried running the heat pump for 24 hours over a period of 2 to 3 weeks, they have tried to heat the home to either a higher or lower temperature (both ideas, as advised by various people) but to no avail, they still get condensation. In two cases they have double glazing.
Condensation can only be removed by introducing dry, fresh and wherever possible warmer air through your home by a continuously controlled ventliation system, which complements a correctly sized heatpump. Heating only enables the moisture to be held in or absorbed by the air. When you use a heat pump we tend to heat for longer and this therefore gives us the idea that the house is dryer but then we get more condensation the following morning.  

If you have condensation and want to get rid if it click here.

When we see condensation as a problem we tend to stick to just one thought and that is just to remove the condensation, what we forget is that our cold bed in winter (caused by winter dampness in our home) is also our hot sticky bed in summer (caused by the summer humidity in our home).

Condensation is only a signal that we have too much dampness in our home, some people believe that condensation is only a problem in winter. The results that we see are only in certain weather conditions that often occur in winter but as many of  you know our weather in New Zealand around christmas can even cause condensation to appear (and thats in summer).

This tends to show that it is conditions, rather than time of year, that causes condensation, therefore continuous year round ventilation is required to successfully remove excess moisture from our homes helping to keep your home dry,efficent and healthy for your family.

To Remove condensation and make your home healthy contact me here

The weather we’ve had over the last few weeks has been great with cold nights, frosty mornings and fantastic days.

These conditions give us lovely fine days but also perfect conditions to produce bad condensation on windows including some double glazed window frames.

On these cold nights we heat our homes more, this in turn draws more water out of our carpets, curtains and all other porous surfaces. Heating the air enables it to hold more water vapour, this we don’t notice as we are warm and cosy – and what we don’t realise is that it costs us to keep the water as vapour. While the air is kept warm the water vapour will stay suspended, once the air cools the water falls out of the air, back into our carpets and furniture and condenses on all non porous and cold surfaces which is generally our windows (I have seen condensation on marble/granite coffee tables). This water stays in our fabrics and carpets until next time we heat the room sufficiently enough to draw it into our home atmosphere, increasing the cost of heating our home   

In these conditions even double glazing can have condensation appearing on the aluminium joinery in far greater quantities (again water that still needs wiping up along with possible damage to your window sills). 

To reduce or most likely remove condensation completely we need to remove the cause not just put a Band-Aid over the results of having a damp or humid home.

Many people believe that completely insulating our homes and installing double glazing will fix our condensation problems but all they do is mask the appearance of condensation on our glass or even our walls.

In insulating and double glazing our homes we reduce the heat loss, which is great, but we also reduce the breathing of the home and therefore reduce the ‘ventilation’ of the home. In doing this we will increase the moisture which will in tern make the home less efficient, colder and more costly to heat. Feel colder, because the home will be damper and more costly to heat because the dampness has to be heated first.

To make your home more efficient you need to remove moisture and lower the relative humidity in our home. Doing this will make your home easier to heat, more comfortable to live in, healthier and reduce overall maintenance.

It is two story with exposed beams in both the lounge and the master bedroom,

Downstairs we have the lounge, kitchen, dining room, bathroom and two very cold and damp bedrooms. Upstairs is the master bedroom, ensuite and an office, these cover less than half of the downstairs floor area.

In the lounge is a large wood fire which heats up the lounge quite easily, some of this heat goes up the open stairwell to the upstairs rooms and helps keep these rooms  warm, but as they still get condensation the windows are left open to ‘ventilate’ these rooms.

 The home owners want to move heat from the lounge to the two cold damp bedrooms.

Now a couple of things to note:


When a house is heated with a wood fire (or any type of heater) the warm air in the room will be able to hold more moisture and as this occurs the warm air draws moisture out of the fabrics, carpets and furniture in the room, now this is how the room will feel both warmer and dryer, it is also the reason we get condensation, as all we are doing is pulling the moisture out of the room then as the room cools it falls out of the air on to our chairs carpets and condenses on our windows. This heated moist air takes up more space and is effectively expanded into the room next door and down the passage if it can as there really is not much airflow as such through a house unless we force it.

If the wood fire is continuously stoked 24 hours a day it may over time dry out our home, but as soon as the wood fire goes out the moisture will immediately be absorbed back into all surfaces and fabrics, all waiting to be heated next time the wood fire is lit allowing the cycle to begin again with the bedrooms becoming colder and damper as the moisture stays there even when you open the windows.


When you transfer heat from 1 room to another through a heat transfer system into bedrooms you are actually pushing moisture laden hot air into a room that is already cold with damp carpets and a damp bed ( many people tell me that the bed is not damp – yet once the ventilation system is installed they tell my how they love their dry bed).

If there is any mould in the bedroom you will at this point be feeding the mould with warm moisture – ideal for growing more mould. The room will initially feel warmer, yet over time will become harder to heat, feel colder, damper, get more condensation and grow mould, and the cycle will continue over and over.


Keep your home dry on a continuing ongoing basis (the reason for this is that any family continues to make moisture at all times of every day), by using mother nature to vent filtered fresh dry air from your roof cavity into all bedrooms and lounge this will kill off all mould spores, warm up and dry out your beds, dry out your carpet and stop condensation, doing this, will make your whole home much healthier and easier to heat. 

This is done by installing a well designed home ventilation system in your home, in this case one with a heat transfer as part of the design and configuration to heat the cold rooms with the excess heat from the lounge wood fire. In doing this the home will have dry natural fresh air pumped into the entire home on an ongoing basis (at variable speeds automatically to suit the conditions) and when the wood fire heats the lounge the excess warm air is taken into the bedrooms to keep them comfortable. Then when the wood fire goes out the system will continue to circulate dry air to remove moisture and stop condensation.

Drying out a home is a year round continuous process, make your home fresh and cooler in the summer and warmer drier more efficient and cheaper to heat by installing a well designed and adaptable home ventilation system.