12aug woodpile hero
13 August 2015

Heating and energy questions answered

Our technical writer George Block shares his advice.

We recently asked our Facebook followers if they had any questions for our heating and energy expert George Block. Here is a selection of the questions they asked and George's responses.

When will batteries be available to store energy from solar power? Which company offers the best rates for solar power? Marianne

There are already batteries available to store power from solar panels, but they’re usually the most expensive part of a solar system, running well into the thousands if you want to power your whole home. If you’re connected to the national grid, it’s more economical to use a "grid-tied" PV system, meaning you sell power into the grid when you’re producing more electricity than you need and buy extra power from the grid when your panels aren’t producing enough. But be aware you can’t use the grid as a "free-battery". Generally power companies will only buy power from you at wholesale prices (3-10cents/kWh). As for which company offers the best rates for solar power, it really depends on how big the system is, where your house is located, how cheaply you can source panels and an inverter, and whether you take the environmental benefits into account when conducting your cost benefit analysis. See our article on grid-tied solar systems to learn more.

Where do you dispose of eco bulbs? Donna

CFL eco bulbs and fluorescent tubes contain a small amount of mercury, so special care should be taken that you don’t break them (although the Ministry of Health found there was minimal health risks associated with broken CFLs). To dispose of CFLs, put them in a sealed glass or plastic that may be available.

Better heating option - heat pump or flued, mains gas fireplace? Darren

It really depends on what you want from your heater. Our recent energy survey found the cost of running a heat pump was generally pretty close to running a mains natural gas heater of the same capacity. The advantage of heat pumps is they can come with a range of other features like timers, cooling and dehumidifying. Gas fireplaces have the advantage that they won’t need to go into defrost mode when temperatures drop, unlike some heat pumps. Many people also prefer the toasty radiant heat of a gas fire to the gentler, background heat of a heat pump.

The most important thing when looking for a heat pump is to select the right-sized model for the space you’re trying to heat, then to select an efficient model of that heating capacity. Consumer NZ membership gets you access to our database and evaluation of more than 140 heat pumps. If you’re considering a gas heater, take a look at EECA’s list of gas heaters that earned an energy star. Please note that we strongly advise against the use of unflued gas heaters indoors as they pose a serious health risk if they malfunction.

Why is that energy saving light bulbs flicker when turned off? &are they using power while flickering? Dawn

This flickering is most common with two-way switches where you’ve got two different switches allowing you to turn the light on/off at different locations, for example in hallways or staircases. Some types of bulb seem to be more prone to flickering than others, so try buying a different make of bulb, and making sure you’ve got the right wattage for the fitting. If problems persist we recommend getting a qualified electrician to take a look at the wiring.

If I want to buy a LED light, what is the equivalent to a 100W bulb? I am completely baffled by this. Michele

The best indicator of an LED’s brightness is the lumens, which measure the bulb’s brightness. The packaging of LEDs will usually also indicate the equivalent wattage of incandescent bulbs that produce a similar brightness. For example, a 14W LED will generally be the same brightness as a 100W incandescent and produce 1300 lumens. If you want to replace an existing incandescent bulb with an LED, use the wattage of the old incandescent as a guide. See our free LED buying guide to learn more.

Are there companies or people that are not selling anything that can consult on best energy solutions for home. Especially if it's a complicated design. Manoja

The Eco Design advisor service provides free independent advice on how to best use energy, water and materials in building and renovation project. The service is available in Auckland, Hamilton, Palmerston North, Kapati Coast, the Hutt Valley, Nelson and Invercargill.

The Community Energy Network focuses on improving the energy performance of existing homes. It consists of a number of independent non-profit energy trusts. Advice is predominantly free.

If you’re after more technical information, BRANZ makes a number of their publications free online – but they’re generally more technical and oriented to the building industry.

If you’re a Consumer NZ member you can contact our impartial advisory service.

How much mercury and other pollution is in these energy saver lights? Luke

It depends on the type of bulb: CFLs contain mercury, while LEDs don’t. That being said, the amount of mercury in CFLs is very small (less than 5mg), and it’s only released if the bulb is broken. A 2008 study by the Ministry of Health into the risks of mercury exposure from broken CFLs found the concentration of mercury in the air resulting from a broken CFL was not likely to be a health risk, even if the bulb was not cleaned up immediately. That being said, we recommend cleaning up CFLs immediately if they break and ventilating the room for a few hours – it’s best to be on the safe side. If you’re concerned about mercury pollution from CFLs, they may wish to use LEDs instead. There is now an LED available for virtually every lighting task in the home that’s a match for CFLs or halogens.

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