|
Heat Pumps Blamed For Power Bill Rise
As winter weather bites, so have the electricity bills, with heat pumps being blamed for skyrocketing accounts.
Some South Island consumers who complained after seeing their power bills more than double from last year have been told there is nothing faulty with their metering or billing.
Contact Energy told the Southland Times it had investigated a number of complaints this week, including from customers who had power bills leap by more than $500.
Retail general manager Jason Delamore said the company had looked into each case and established a change in user patterns, such as the installation of heat pumps and the use of oil column heaters, was behind the increase.
Contact communications manager Jonathan Hill said estimated accounts were based on usage at the corresponding time the previous year, so if the company was unaware of change in energy use, the next actual reading would factor in a significant catch up.
The installation of a heat pump in Christchurch woman Selena Cannell’s home was ‘almost certainly’ the key reason her bill had more than doubled from $160 in May to $400 in July, he said.
Heat pumps were efficient but still impacted heavily on power bills, Mr Hill said.
‘There is a perception out there that heat pumps are almost free to use – that is not the case at all’
‘We don’t think it would be uncommon for people who are running them really hard to incur costs of up to $5 per day’ he said.
Trustpower staff told disgruntled Timaru customer Moira Melhopt that aheat pump could cost up to $7 a day to run’
‘More and more New Zealander’s are getting heat pumps, so all retailers will be facing similar issues’ Mr Delamore said.
However, Ms Cannell disputed Contact’s claim a heat pump had caused her power bill to double.
The company that installed the heat pump had told her it should be costing only $60 to $70 maximum a month’ she said.
Ms Melhopt said she felt disappointed about what she had been told.
‘We have been promised efficient heating and therefore lower costs with a heatpump’
Daiken New Zealand, which specialises in heat pumps, said they cost between 10c and 20c an hour to run.
New Zealand Herald - August 1st 2008
Roof space air insufficient in heating many homes
Ventilation systems which move air from the roof space around a home should not be promoted as heating and cooling systems because heat generated in the roof of some New Zealand wooden houses is insufficient to heat homes in winter, a University of Otago researcher says.
In fact, on average the highest generation of heat, in a wooden, pre-1940s house, was only the equivalent to the heat output from five 100-watt light bulbs, University of Otago Energy Studies graduate Warren Fitzgerald found.
Mr Fitzgerald's findings have been published in the Energy and Buildings journal.
The highest average cooling potential of pumping cool air down from the roof cavity was about 1 kW.
"The majority of the time, it was calculated that pumping air from the roof space into the house would provide little heating or cooling benefit. In fact, this would often actually act to push the internal temperature in the house further away from the desired level rather than closer to it," Mr Fitzgerald said.
His study used a computer model of a typical older-style New Zealand weather board house with a pitched iron roof, and ceiling insulation, located in Dunedin. His experiments transposed the computer-model of the Dunedin house to three other main centres -- Christchurch, Wellington and Auckland -- then added weather data from the NIWA website for these centres.
He then ran the experiment over continuous ten-day periods in January, April, July and October -- to represent the four seasons.
Project leader and University of Otago physics research fellow Inga Smith said based on these results they recommended existing positive pressure mechanical ventilation systems should not be promoted and marketed as heating and/or cooling systems.
"In essence, this research shows that there is a very small amount of free heat available, but this is often not available when it is needed the most during winter."
Dr Smith said the experiment did not test the ability of systems to control moisture or humidity in houses.
Click here to download Roof space air insufficient in heating many homes
Roasting for airing systems' heating
Catherine Harris
A NEW study has “well and truly busted” the diea that home ventilation systems alone can adequately warm up a house, according to Consumer magazine.
The Otago University study found that “positive pressure” ventilation systems did now draw down enough heat from the roof cavity to significantly alter the temperature of a typical pre-1940s wooden house in winder. It found that at best, the system averaged the heating power of five 100-watt light bulbs.
Project leader Inga Smith recommended that such ventilation systems should not be marketed as “heating/cooling” systems.
Constumer research and testing manager Hamish Wilson said he was delighted to see the study's results. The systems were effective at tackling condenstaion he said. But “we have for a long time maintained that there won't be warm air up in the roof space on frosty nights and cold grey winter days”.
Mr Wilson said it was misleading to claim ventilation that used roof space air could heat or cool houses, and it was also untrue that it controlled dust mites.
Ten per cent of homes are estimated to have some form of ventilation system. A positive pressure system ranges in price from $1000 for a DIY job, to $5000 for an installed, top-of-the-line version.
But installers said the study failed to consider the wider benefits of ventilation. Bon Batenburg, of Healthy Home Group, which markets DVS systems, said his firm was careful in its claims. “We don't say it is a heater.”
But he said the systems could still assist theating by driving houses out and warming rooms on the cold side of a house on sunny days.
Iain Hosie, a spokesman for HRV, said the study was too narrow. “The study focused on the heating and cooling benefit which is not the primary purpose of ventilation – which is to regularly change the air to maintain good indoor air quality.”
Click here to download Consumer Magazine Article on HRV Systems
“Free heat” myth busted
We've all seen that TV ad with sausages grilling on a hot tin roof. The implication is that there's loads of free heat under the roof for keeping your toes warm in winter.
It's a myth that's just been busted.
A University of Otago study of the roof-space temperatures in iron-roofed Kiwi bungalows has found it's more likely to be like a fridge up there when it really matters – in the middle of winter.
It may be sauna-like above the ceiling in summer. But the Otago study says that on frosty nights and cold grey winter days pumping in air from the roof space can often make your house colder. We aren't surprised. More than a few members have written to us with a simple complaint: since they've installed a positive pressure ventilation (PPV) system that sucks in air from the attic they've been feeling the chill.
And it gets worse... the research also shows that these ventailation systems can often make your hosue hotter than you'd like in summer.
The Otago study shows there's not abundant free heat (and free air conditioning) from the PPV type of ventilation system. On a sunny spring day you can expect at best about as much heat as you'll get from five 100W lightbulbs. That's hardly going to raise a sweat or grill a banger.
Some advertising also claims that ventailation systems will help asthma sufferers by controlling dust mites. That's unlikely too. A study of housing in Wellington by the Wellington School of Medicine and Health Sciences showed no reduction in house mite numbers after ventilation systems were installed. In our damp rainy winders, there's just too much humidity to get our house interiors below the magic 50 percent humidity needed to control the dust mites which are linked to asthma.
PPV ventilation systems should be promoted on their ability to provide enough ventilation to control condensation – and that's all. In the right housem, improving ventilation by mechanical means can reduce or even eliminate condesation.
MORE INFO Ventilation systems:
www.consumer.org.nz
Click here to download Independent Study on HRV Claims
Ventilation installer disputes claims of heat from pressure systems
Catherine harris
An experienced installer in the home ventilation industry says consumers are being deliberately confused by come companies so as to sell more product.
Gordon Buick, a Foxton installer and owner of heater company Therm.r.duct, concurred with a recent Otago University study that said “positive pressure” systems which use “free heat” from the roof cavity do not make houses warmer during the cooler months.
Consumer NZ welcomed the study, saying some advertising had been misleading.
Mr Muick, who worked for the British company which devised the systems originally, said the ventilation industry had been advised to regulate itself but had been unable to find consensus.
He said positive pressure systems were never meant to provide anything other that ventilation without and energy-efficient heater, but some firms had failed to make this clear.
And they had been telling customers they needed more ventilation outlets than necessary. “The commision agents, which are domination the industry now, are being told what to say and they're not explaining to people that they could have one vent if they were happy to leave their doors ajar. Obveiously it's not illegal but neither is having half a dozen toilets in the house.”
Mr Buick also took a swipe and the Energy Efficiency and Conervation Authority, which maintains that opening windows gives modern houses sufficient ventilation.
“We've been [so] paranoid about keeping the heat in with the high prices that we're trying to make our homes as air-tight as possiblem but... the moisture laden air can't get out”
EECA senior technical adviser Christian Hoerning said the windows advice was “a sufficient option” for most houses, but for security or draught reasions, not everyone wanted to leave windows open.
He denied EECA was ignoring the ventilation spect of its “heating, insulation, ventilation and moisture control” message.
“We are actually quite expliciet about it's more that one thing that you need to look at to create a warmer, drier, healthier home.”
Mark Bassett, principal scientist for the Buildign Research Assosiation Branz, said ventilation systems were “one of the lease effective ways of dealing with moisture” comared with dealing with it at source.
“There are more effective methods... such as rangehoods and bathroom extractor fans.”
Meanwhile, EECA chief executive Mike Underhill said his body would be prepared to take action under consumer laws if ventilation companies continued to mislead.
“We will keep an eye on this in the shore term and we will challenge the companies, the very few that are making heating claims, as to how they can jusitify those claims.”
Click here to download Ventilation Installer Dispute of Claim Article
|
