Double glazing, dampness and condensation

Double glazing is big business these days. The building code now effectively requires all new homes to be fitted with double glazing, and the market for retro-fitting double glazing to existing windows is booming.

I'm a big fan of double glazing. It's an excellent way to insulate the window system.

However, there's one common misconception being promoted by the majority of double glazing companies that I'd like to dis-spell.

Reduced condensation does not mean reduced dampness and moisture

Condensation is a common problem for homes in New Zealand, and double glazing does help to prevent condensation from forming on the inside glass surface. It does this by making the inside glass surface warmer, which means the moisture in the air around the glass doesn't condense.

However, this doesn't mean the moisture has magically gone away. It's still there, in your home.

In fact, the newer the windows, the more air tight they'll be, so installing double glazing, or retro fitting double glazing to existing windows actually tends to increase the moisture levels in the home. It's just that you don't notice it as much because you don't see it on the windows.

So why is excessive moisture a problem? You may ask, if you can't see the moisture on the windows, is it really a problem? Yes it is. Excessive moisture or dampness leads to mould and mildew growth. It's also linked to asthma and other respiratory health problems. Dampness in the home also damages furnishings and fittings over time, leading to costly repairs and maintenance.

Just because the moisture doesn't condense on the windows anymore, it doesn't mean it goes away. It lingers in the home and when the temperature of any surface drops below the dew point, it condenses on that surface. This could be your bedding and furniture, or your carpet or your clothes.

What about indoor air quality? Indoor air quality is a measure of the level of CO2 and other pollutants in the air. Double glazing does nothing for improving indoor air quality. In fact, because the home often ends up more air tight after it's installed, the indoor air quality is usually worse.

So how do you properly address moisture and indoor air quality? The answer is Ventilation.  Ventilation allows the damp, polluted indoor air to be gently replaced by drier, fresher outside air.

And yes, the outside air on a cold wet winter's day is still far drier than the air inside your home - in fact the colder the air, the less moisture it can hold. This is why condensation forms in the first place. The air temperature around the surface drops, the colder air cant hold the moisture any more, so it releases it as condensation.


In the majority of homes, natural or passive ventilation is more than sufficient to meet your ventilation needs. Natural ventilation can be achieved by leaving your windows slightly open all day and night, although this is not really an option for most households these days. There are security issues, insects can come inside, and it also tends to over-ventilate, causing excessive heat loss.

A far better solution is to install secure passive vents into the windows. These can be left in the open position 24/7, providing secure, low-level continuous ventilation without any noticeable heat-loss. The market leader in retro-fit passive vents is Easy Air. These are also ideally suited to being installed at the same time as double glazing, whether it's new windows or if you're double glazing existing windows.

Comparison of home ventilation solutions matrix

	Secure trickle vents	Opening windows	Positive pressure systems (HRV, DVS etc)	Balanced pressure systems (with heat exchangers)
Controls condensation	Utilises cross-flow ventilation to replace damp air with outside air which has a lower total humidity than inside air and roof space air.	Uses cross-flow ventilation to replace damp air with drier outside air	Uses a fan and ducting in the ceiling space to force roof space air into the home, displacing damp air through external openings. Controls condensation as long as the roof space air has a lower total humidity than the inside air (not always the case)	Yes. Uses outside air which has a lower total humidity than inside air or roof space air.
Minimses heat loss	Yes. Does this by providing a small, but effective opening size. Cooler outside air is quickly brought up to inside temperatures	Controlling unwanted heat loss is difficult with opening windows. Even slightly open windows result in over-ventilation and excessive heat loss in the winter	Relies on the natural thermal properties of the roof space since the input air comes directly from the roof cavity. This air is often colder than outside during winter periods	Yes. All incoming air is preheated to some degree by the outgoing air.
Recovers heat	No	No	Strictly speaking "no". Positive pressure systems simply force roof space air into the home. During warm periods this air is warmer than inside. During cold periods it's colder than inside. Some times it's even colder than the outside air. So while the roof space generates a large amount of "free heat" over the course of the year, it doesn't store the heat, so it's not usually there when you want it.	Yes. The warm but damp inside air is passed through a heat exchanger where the heat is partially transferred to the cooler incoming air, but the moisture is not. This means that, for example, the heat from steamy bathroom air can be used to pre-heat the fresh air coming in.
Provides cooling in summer	Minimal. The vent openings are not generally sufficient for significantly cooling a home down on hot summer days.	Yes. This is still the easiest method for controlling heat buildup in a home, although it's not a secure solution	Standard installations do not cool in the summer. In fact, the uninsulated roof space can get very hot during the summer, causing the system to either shut down, or pump hot air into the home. Summer kits can be added, which simply bypass the roof space.	In combination with a heat pump / air conditioning unit, it can make the air conditioner more efficient by passing the cooler inside air through the heat exchanger to pre-cool the warmer incoming air. This only works if the inside air can be kept cooler than outside.
Security	Totally secure. System is glazed in to the window system.	No. Even with double tongue latches or security stays, a window left ajar is an invitation to burglars	Totally secure. As the input is through the roof space.	Totally secure. Input and output is generally through the roof
Insect proof	Yes. Most secure trickle vents have an insect mesh which prevents all insects from getting inside	No. Flies, mosquitos and other pests can and do get in through an open window.	Yes	Yes
Cost	Low - Generally $1,000 for a 3 bedroom home. Can also be used to cost-effectively ventilate smaller buildings for a per vent price.	Free	Medium to high. The total cost depends on the number of outlets and the system used, but costs generally start at about $2,000, and are typically more like $3,000 - $4,000	High. Again, the cost will depend on the size and type of system, but prices generally start from around $4,000 - $5,000
Ongoing running costs & maintenance	None. Trickle vents are maintenance free (apart from the occasional wipe down), normally guaranteed for the lifetime of the window, and they cost nothing to 'run'	None	Filter changes every 1 - 2 years. These can be in the range of $300 - $400 per change. Although you can DIY if you want to save some money. Power consumption. The fans are quite low wattage, but there is a cost to your power bill. Maintenance. The systems may need repairs and maintenance. Warranty periods vary, but the system may need to replaced after 10 years or earlier.	Similar to Positive pressure systems although the systems have 2 fans, so the running costs may be marginally higher

How To Make Electricity - Never Again Pay the Electric Company

By Bob Langford


If you'd like to know how to make electricity for your home instead of relying on your local power company, this article is for you.
There are a few ways to generate electricity, but only one way that is virtually free to build, maintain and run. With that said, let's have a look at the contenders:
Wind Mill Energy:
Apart from the obvious disadvantages, like a large wind mill hogging up your back yard, getting city permits to put it up and a large upfront cost to purchase one, a windmill is not going to give you much juice unless you live right by the edge of a rugged ocean.
Solar Energy:
Solar panels are great if you're a large corporation, but for residential homes they can be very costly, and they only work effectively in consistently sunny climates. Furthermore, in order to be effective, they will take up a large part of your roof, and they are damage prone in rough weather.
Put simply, while these contenders work for municipalities and corporations, they are not good alternatives for using in our homes. This brings us to the 3rd contender, which is ideal for using in the home:
Magnetic Power Generation.
A magnetic power generator is fully independent, which means that it works equally in any temperature or weather. It also runs completely clean, and is virtually free to build and run. But it doesn't stop there:

• When the rest of your town has a power outage, you'll be unaffected
• It's easy to build, even if you are a beginner
• It's completely safe to use for you and your family
• It works in every home, anywhere and takes up very little space
• The material needed to build your magnetic generator is very cheap, and easily accessible anywhere you live in the world
• It creates an abundance of electricity, which can eliminate your power bills entirely
• It runs completely clean, with zero harmful byproducts being emitted

As a matter of fact, magnetic power generators are so powerful that large money corporations have been suppressing information about their technology. They do this because the impact of this technology, should it catch on, threatens their future stock.
It's estimated by many that magnetic power-generated energy will start dominating the world market within the next two decades.
But why wait when you can literally be your own power company - this week? And yes, it is that easy, and it is cheap.
Not only will it save your family and yourself thousands of dollars on power, but you'll be sleeping soundly, knowing that you've made a wonderful environmental contribution to the planet. To find out how to make electricity by building and using a magnetic power generator, click here to go to the next page.

Article Source: http://EzineArticles.com/?expert=Bob_Langford


http://EzineArticles.com/?How-To-Make-Electricity---Never-Again-Pay-the-Electric-Company&id=5019954

Comparison of Home ventilation solutions part 1

We all know that effective ventilation is an integral part of maintaining a healthy home environment. Or at least we should know.

Ventilation removes moisture and airborne pollutants from the home and replaces this 'bad' air with drier, fresher air from outside.

The energy cost of ventilation

Ventilation is often the poor cousin of the critical triple act of Heating, Insulation and Ventilation. They're all equally important to maintaining a healthy indoor environment.  Unfortunately, due to our current fixation on reducing energy consumption and reducing our electricity bills, ventilation often gets forgotten or ignored.

Put simply, there is an energy cost to maintaining effective levels of ventilation. If you're expelling the damp, stale (and warm) air, and replacing it with fresher, drier (and cooler) air from outside, then you obviously need to heat the new incoming air.

But what's the alternative? Seal up your home to retain all that hard earned warmth and keep out the cold outside air? Considering an average family generates in excess of 12 litres of moisture per day (and that's conservative), it's not rocket science to see that the moisture content of the inside air will very quickly increase to unhealthy levels. This will lead to condensation, mould and mildew and unhealthy occupants.

Heat loss is an inevitable side effect of proper, effective ventilation. The key then is to achieve the correct rate of ventilation to control indoor humidity and pollution, whilst not losing more heat than is necessary.

It's worth noting that drier air takes less energy to heat than damp air, so if you get your ventilation rates correct, the cost to your heating bill can be quite minimal.

Factors in deciding on the right ventilation solution

So which ventilation solution is right for me, I hear you ask.  As you'd expect, this is not a straightforward answer. It depends on quite a few factors including:
- Building airtightness
- Location
- Local weather patterns and temperatures
- Building construction characteristics
- Occupant's behaviours and lifestyle
- Building design and layout
- Cost

Types of ventilation

Before we look at these factors in more detail, I'll introduce the main methods for ventilating a home, running roughly from cheapest to most expensive:

Passive ventilation

This is where the naturally occurring pressure differences around a building are harnessed to draw fresh air in and suck stale air out.

This is the way homes have been traditionally and successfully been ventilated for centuries and since the principles haven't changed, neither has the validity of this approach. There are two main principles that can be used:
1. Cross-flow - Where negative pressure on the sheltered side draws air out through openings and replacement air is pulled in through openings on the windward side
2. Stack effect - Where warmed air in the building rises and exits through openings in the top of the building and replacement fresh air is drawn in through openings lower down. This is also referred to as the chimney effect, since this is exactly how chimneys work.

In practice, passive ventilation can be achieved by opening windows, installing secure trickle vents, usually in the window system (www.easyair.co.nz), or by installing roof vents to take advantage of the stack effect, with trickle vents for the replacement air.

Passive ventilation is effectively the main method for meeting the building code requirements. These stipulate that openable windows, equivalent to not less than 5% of the floor area in a room must be installed. This of course makes an assumption that these windows will be opened from time to time, which in practice doesn't always happen, for reasons of security, weather, insects, noise and heat retention. This is where passive vents come in. They are usually installed securely into the window system. Some can be retro-fitted to existing windows. They provide a controllable level of ventilation, they are secure and they will keep out insects and weather. As they rely on natural pressure differences around the building, they are better suited to buildings which have reasonable exposure to the wind, although only the most sheltered of buildings would not benefit from passive ventilation.

Passive ventilation with intermittent extraction

This solution uses intermittent extractor fans in wet areas (i.e. Extractor fans in the bathrooms and rangehoods in the kitchen). These extractors must be ducted to the outside. They also need to be switched on long enough to remove the majority of moisture created when showering, cooking etc. It's recommended to have them either over-running on a timer, or to have them hooked up to a humidity switch so they automatically switch on when humidity gets above a set level.

To operate efficiently, extractor fans rely on passive vents to replace the air being extracted. They can only extract air if it can be replaced with fresh air. So passive vents are an integral part of this solution.

Passive ventilation with continuous mechanical extraction

This uses the same principles as above. Basically the house is under continual negative pressure, where an extractor fan mounted in the roof space draws air from one or more rooms through ducting and expels it from the house. Passive vents are positioned around the home to provide fresh replacement air. Again, without the passive 'inlet' vents, the system won't extract air at the rate required. It would rely on windows being left open which is inefficient and a security risk.

Positive input ventilation with passive outlets

This is essentially the opposite of the above system. A fan is housed in the roof space with ducting to one or more inlets through the ceiling. Air is blown from the roof space into the home, forcing the damp air out through openings, usually in the form of passive trickle vents. Although the vendors in NZ (e.g. www.HRV.co.nz) often simply rely on natural air leakage of the building, or on open windows. This is very variable depending on the house construction, and installing specific outlet vents would seem a much more reliable approach. Pushing air into the home rather than extracting it out also means the ventilation is less targeted, and path the air takes is more difficult to predict or control.

To counter these shortcomings, the companies promoting these systems emphasise that the roof space air is warmer and drier than outside, so there is some heating benefit from doing it this way.  This strikes a chord with homeowners in the current climate where reducing heating costs is a hot topic.

However the heating benefits have been questioned by a number of studies both here and overseas, and it appears the ability of these systems to provide free heat at the time of day, and year, when you actually want it is marginal at best. In addition, the roof space is often too hot during the summer, requiring a summer bypass to be installed, usually at extra cost.

One of the draw backs to a ventilation system claiming to also provide heating is that, when the roof space temperature doesn't suit (i.e. it's either too hot or too cold) the ventilation fan either slows right down or turns off. This means that the system is now not even providing ventilation, which is it's primary function.  Since ventilation is about maintain moisture levels in the air, any automatic controller should be based on humidity, not temperature.

Mechanical Extraction with Heat recovery

This system is a balanced pressure system, usually incorporating an input fan, an output fan and a heat exchanger. Fresh air is drawn in through ducted vents (usually under the eaves). This passes through the heat exchanger which transfers some heat (but not moisture) from the outgoing air to the fresh incoming air, essentially pre-warming it.  The warm air from the home is extracted through ducting, passes through the heat exchanger where its latent heat is transferred to the incoming air before being expelled to the outside.

The obvious key benefit of these systems is that they use a percentage of the residual heat from the extracted air to pre-warm the incoming air, thereby reducing the cost of bringing this fresh air up to temperature.  In the summer time, they can also work in reverse, as long as you have a way of keeping the inside of your home cooler than the outside (i.e. with an air conditioning unit). During the summer, the cooled inside air is passed through the heat exchanger to cool the hot incoming air.

Balanced pressure systems such as this (e.g. www.loss-nay.co.nz)are the only system where passive inlet or outlet vents are not recommended. These systems rely on the building being as airtight as possible so that all air coming and going is passed through the heat exchanger. Any additional gaps will reduce the efficiency of the system.

In the next section we'll compare each option with the determining factors - Read on >>

Understanding Condensation

There seems to be a lot of mis-information and mis-understanding about condensation. What causes it? How do you reduce it?

This mis-information often leads home owners to spend a lot of money trying to treat the symptoms, rather than actually tackling the cause.  In fact, addressing the causes of condensation is often a lot cheaper than installing a system to constantly manage the symptoms.

So, where to start:

Moisture and Relative Humidity

First we need to understand the basics about water vapour in the air.

At any specific temperature the air can hold a certain level of water as vapour - the warmer the air is, the greater the potential amount of water vapour it can hold. For example:

Air at 10ºC is saturated (or at 100% RH) when it contains 7.6g water per kg dry air.

Air at 20ºC is saturated (100% RH) when it contains 15.3g water per kg dry air.

Relative Humidity (RH) is a measure of how 'saturated' the air actually is, expressed as a percentage, i.e., what is the proportion of actual water vapour compared to the maximum amount that can be held at a given temperature.

So, using the examples above, air at 10ºC, containing 7.6g water per kg dry air has a relative humidity of 100%

But, if this air is warmed to 20ºC, and it still only contains 7.6g water per kg dry air, then it's relative humidity is only 7.6 / 15.3 (water holding capacity) = 49.7%

So, when the total moisture levels don't change, as you warm air, it's RH drops. Conversely, as air cools, it's RH increases. This is an important thing to note, and goes a long way to explaining condensation.

The Dew Point

So we now know that cold air cannot hold as much water vapour as warm air, and that as the temperature drops the relative humidity increases. An often used illustration is that of a bucket of water.

Think of the air as a 'bucket' holding an amount of water. The size of the bucket denotes the temperature, higher temperature = bigger bucket. Lower temperature = smaller bucket.

As the air is cooled the 'bucket' get smaller and therefore the proportion of water increases.  If air continues to be cooled, the 'bucket' shrinks until it's completely full of water (this is the DEW POINT).

Now, if the bucket gets any smaller (i.e. if the temperature goes any lower) the water will overflow and spill out of the bucket. This is what condensation is. It's the excess water that the cooled air can no longer hold.

So the DEW POINT = The temperature at which condensation begins = the point where the Relative humidity is 100%

Causes of Moisture

In a typical home, the main creator of moisture is us, humans. We breathe, we cook, we shower, we water pot plants, we dry clothes inside. Some of these things we can minimise or eliminate, others we can't.  A watertight, unoccupied home will generally not suffer from condensation.

Windows and double glazing

Condensation usually forms on the windows simply because the air around those surfaces is usually the coldest. It's usually coldest because the cold air against the outside glass surface is very easily transferred through the glass to the inside surface. Glass is a great conductor of cold and heat, unfortunately. This is why double glazing helps to reduce condensation, it simply makes the inside glass surface less cold. It doesn't actually do anything about reducing the cause of condensation, which is the level of moisture in the air.

The importance of ventilation

Now that we've ascertained that condensation is caused by the temperature dropping to below the dew point for the level of moisture in the air, it should be clear that the two ways to prevent condensation are to either keep the temperature above the dew point, or to reduce the amount of moisture in the air.
If we only focus on keeping the home warm, we'll soon come unstuck. The average family is producing around 12 litres of water EVERY DAY (much more if you believe some advertisers). So as the moisture levels increase, we'd need to keep increasing the temperature to stay above the dew point until we ended up in a very uncomfortable environment indeed.
By far the best and most sustainable way to control condensation is to control the moisture levels in the air. This is done by minimising the amount of moisture is introduced into the home in the first place (i.e. not drying clothes inside, extracting steam from the bathroom before it gets into the rest of the house), and using ventilation to manage the remaining moisture, replacing it with drier air from the outside.

As we've learnt above, while the air from the outside is no doubt colder than inside, it's also a lot drier because:
a) it's cooler so can't hold as much water
b) it's not trapped in an enclosed space with moisture generating humans increasing it's humidity.

If you draw in this outside air to replace the damp inside air on a continuous basis, and at a level that doesn't mean losing more heat than is necessary, and if you maintain the indoor air temperature at a level higher enough to keep indoor surfaces above the dew point, then you will not have condensation.

Smart houses a reality

This article in stuff.co.nz discusses a house that can sense the changes in weather and react accordingly to maintain an optimal indoor environment. Worth a read...
Smart House Can Predict Weather

Heat Pumps - How they work, efficiency, price and installation

How does a Heat Pump work?

To understand how a heat pump works, you need to first understand how an air conditioning unit or a fridge works.  An air conditioning unit concentrates heat in one set of coils positioned outside your home, and cold in another set of coils positioned inside your home. You can read more about how air conditioners work here.

So, a heat pump is essentially the inverse of an air conditioner, with the hot coils on the inside of your home (via the internal unit) and the cold coils on the outside of your home (via the external unit).

Heat Pumps Efficiency

Heat pumps are very efficient in relation to the energy they use. The energy used to run a heat is not directly used to create heat, it enables the transfer of heat and cold, which can generate around 3 - 5 times the heat output of the energy used to run it.

Most heat pumps can be set in heating or cooling mode. This simply reverses the flow of Freon between the inside and outside coils.

Heat pump price

Common heat pumps brands include Fujitsu heat pumps, Panasonic heat pumps, Mitsubishi heat pumps. You can buy these heat pumps from most appliance stores. Price varies between appliance stores. 

Heat pumps install

Heat pumps need to be installed by an electrician, preferably one who specializes in heat pump installation.