A P R – J U N2 0 1 9

P A G E 4 1

Energy efficiency specialTarget the big energy users in your home! Plus a mechanical ventilation mini guide, tips to manage condensation & more.

P A G E 5 0

Draught sealing buyers guideFix the gaps to beat the chills.

P A G E 3 1

A Stiebel Eltron hot water heat pump valued at up to $5500* Australian and NZ residents only

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Technology for a sustainable future

AU/NZ $9.90RENEW.ORG.AU

A home for all climatesSix comfortable homes around Australia retrofitted to save on energy and bills.

Cover image: Phil Hines Photography. Four years ago, this weatherboard home started a new chapter, becoming one of the first renovations in Australia to reach Passive House standard for airtightness and insulation. The internal temperature now stays around 22 to 24 °C year round, with very little heating and no cooling. Read more in our climate-zone case studies starting page 46.

Apr – Jun 2019

03 – About us

08 – Up front

10 – NEM chat

12 – Products

88 – Letters

90 – Q&A

92 – Pears Report

94 – Classifieds

96 – Member profile

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A hot water heat pump from Stiebel Eltron valued at up to $5500

* Australian and NZ residents only

Averages can be misleading. For example, you could say that, on average, a home in Victoria has about half of a ducted gas heater, 70% of a gas water heater and 7% of a gas-boosted solar water heater. Even though that's clearly a home that doesn't exist, such averages can illuminate issues and trends—and help determine priorities for households wanting to reduce their energy use in different states and climate zones.

Our article on energy use around Australia uses the Residential Baseline Study to show average household energy use by activity (down to the level of clothes dryers, refrigerators, heating and the like) and by state. The big differences are in heating and cooling, as you might expect, but, interestingly, heating emerges as a much larger energy user overall than cooling. The study highlights other differences that depend on historical fuel use and the 'appli-ance of choice' in each state—gas ducted heating is much more common in Victoria, for example. Energy use for appliances like TVs, washing machines and dishwashers doesn't vary much by state; instead, it's the trends over time that stand out, such as the sharp increase when plasma TVs came onto the market, pleasingly reversed when LED LCDs took over. The positive effects that good minimum standards can have on energy use are really evident.

To go a bit beyond the averages, we've also included case studies of house-holds around Australia. Whether it's heating, cooling, buying a smaller fridge or removing 40 halogen downlights, it's interesting to see what's made the biggest impact in different places and different homes.

Being able to control the ventilation of your house, rather than have leaks around windows, doors or even behind built-in appliances, can be one of the easiest ways to improve the performance of your home. Our draught sealing buyers guide this issue looks at where the gaps are—a surprisingly large number of potential culprits—and the different products and methods for sealing them up.

There's much more besides: we look at when condensation can be a problem and what can be done about it; provide a mini buyers guide to me-chanical ventilation, which becomes important as houses become better sealed; look at the impact of ‘always on’ loads in the home—modems, NBN boxes, alarms and the like; look at the economics of solar gardens; cover the latest in electric vehicles; and much more besides, more than I can list here! Enjoy and let us know your thoughts.

WIN!

R E G U L A R S

Robyn Deed Renew magazine editor

I S S U E 1 4 7

16 Load shedding coming to your area soon?We look at how areas get chosen for power outages, and whether rooftop solar can come to the rescue.

21A solar+battery decisionHugh Cross on why he installed a solar+battery system, and how it's working.

27Solar gardens

Can solar gardens help renters, apartment owners and low-income households access the renewable energy revolution?

32Making kerosene historyWhile the western world takes electricity access for granted, a large part of the world has no such luxury. But that is changing.

36Off-grid in the suburbs

Martin Chape has quite a few solar energy systems; his latest is an off-grid system that runs his whole house in the suburbs of Perth.

80 Sheet mulch and compost- DIY

From bare lawn to permaculture paradise: this DIY gives tips and tricks for using sheet mulch and hot composting to improve your backyard.

84 Electric vehicle update- EV

The move to electric transport, in all its forms, is now well under way and 2019 is shaping up to be a very exciting year indeed.

41 Unravelling energy use around AustraliaWhat counts as energy-efficient in one climate zone may be ineffective or unnecessary in another. We dig deep into energy use averages and trends in different states of Australia.

46 Climate-zone case studies- CASE STUDIES X 6

How householders have tackled energy efficiency in their homes around Australia.

50 Draught sealing buyers guide- BUYERS GUIDE

Draughts can make your home far less comfortable than it needs to be. Sealing them up is one of the simplest things to do for an energy-efficient home.

60 Condensation concernsAs our homes get more airtight, it's important to consider ventilation and moisture control to avoid condensation problems.

65Upper storey comfort

Upper storeys are more exposed to sun and wind, and shading can be tricky to manage. So how do you get a good night's sleep upstairs?

68Upper storey case studies- CASE STUDIES X 2

Homes with upper storeys that perform in Melbourne and Brisbane.

70Mechanical ventilation with heat recovery- MINI BUYERS GUIDE

Heat recovery systems bring in fresh air with minimal heat loss. Here's a mini buyers guide on what to look for.

74Small loads that add upWith devices like internet modems that are always on, how much of a problem is that for energy use?

78 Energy-efficient stained glassIt is possible to use old materials in a new energy-efficient build.

A R T I C L E SF E A T U R E S

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8 issue 147 renew magazine renew.org.au

Epic electric-car journeyDutchman Wiebe Wakker has been driving his electric car, called the ‘Blue Bandit’, from Amsterdam since 15 March 2016. By late February 2019, Wakker had arrived in Melbourne, completing a distance of 91,000 km over 1073 days. Wakker aims to prove that EVs are reliable and fit for long-distance travel—just what Australian drivers need—so he has crossed 33 countries in Europe, the Middle East, India, Southeast Asia and Australia, all without visiting a petrol station. The Blue Bandit is powered by a 37 kWh lithium ion battery, with a 200 km range. The AC propulsion drivetrain has a 150 kW motor with two gears (2nd and reverse—the car is a converted VW Golf variant) and reaches a top speed of 180 kph.

Wakker’s Australian journey started in Darwin and continued on to Perth, across to Newcastle via the Nullabor Plain, then north and west through Queensland to Tennant Creek, and south and east to Adelaide and Melbourne. (He did need a tow for the last 20 km to Coober Pedy.) Wakker travels without money, instead relying on people to show their support for his journey with meals,

accommodation or electricity for the plug-in car. He also highlights sustainable projects and companies en-route, and Melbourne residents may have seen his presentation at Renew’s own EV Expo. He plans to create a documentary of his trip once it’s complete, and you can follow his route online as he closes in on his ultimate destination of Sydney.plugmeinproject.com

Repurposing wasteFashion’s environmental impacts go from manufacturing to disposal. It’s estimated that the industry produces 100 billion new garments every year, and YouGov found that one in four Australians have binned clothing after only one wear. It is believed 92 million tons are thrown away every year worldwide and moves are being made to capitalise on these wasted resources. At an industry-wide level, the annual Circular Fashion Conference investigates topics like cradle-to-grave design, sustainable procurement, clothing collection and end-of-life reprocessing for fabrics and dyes. One solution has been found by researchers at Deakin University. Using seed funding from the H&M Foundation, they developed ‘denim-dyed denim’, a process where one old pair of jeans can dye 10 new pairs with zero water use (compared to 200 L/pair in traditional jeans dyeing).

Researchers at UNSW’s Centre for Sustainable Materials Research and Technology (SMaRT) have an even more radical idea: converting old clothes into high-end building materials. Textiles have been repurposed into composite flat panels with a wood-veneer or ceramic-style finish. They have been lab tested for fire and water resistance,

U P F R O N T

Wiebe Wakker’s epic trip around the world in an electric vehicle is set to end in Sydney on 7 April.

Image: Wiebe Wakker

12 issue 147 renew magazine renew.org.au

High efficiency hot water heat pump

Heat pump water heaters are by far the most efficient electric water heaters. The most efficient heat pump unit to-date has been the Sanden heat pump, which uses a very efficient CO2 heat pump system. But because it uses a stainless steel tank, it hasn’t been recommended for areas with harsh water quality, such as homes using bore water.

Reclaim Energy’s new CO2 heat pumps are available with either glass-lined (enamelled) or stainless steel tanks and so cater for all Australian water qualities. The stainless steel model is available in tall or squat versions and is suitable for all water types excluding high mineral and bore water. The enamel tank is suitable for all water types including high mineral and bore water. All tanks are 315-litre capacity, and units are configured as a split system, with the compressor separate from the tank.

Other features include a -10 °C to 43 °C ambient temperature operating range, noise level of just 37 dB, five different operational modes including a solar consumption mode, an input power of just 860 W and a COP of up to 5.6. According to Reclaim Energy, the heat pump will use just 20% of the energy of a resistive element water heater, greatly reducing running costs. RRP is yet to be set.

Contact:

Reclaim Energy, ph: 1300 383 815hello@reclaimenergy.com.aureclaimenergy.com.au

Enphase upgrade

Microinverters have several advantages over string inverters—they allow an array to better tolerate shading as each panel is independent, and the output is regular mains AC, so no DC wiring is required.

Arguably the most popular microinverter has been the Enphase range, with the latest models from Enphase being the IQ 7 range.

The IQ 7 inverters supersede all previous models in Australia and consist of the 250 W (rated output power) IQ 7, the 295 W IQ 7+ and the 320 W IQ 7X (designed for use in commercial systems with 96 cell panels).

All models are smart grid ready, are smaller and lighter than previous models (212 x 175 x 30.2 mm without bracket, weight 1.08 kg) and have fully double-insulated, IP67 sealed enclosures. Efficiency is rated to 96.5% for all models, and of course they have all the previous model’s communications and monitoring features—Enlighten Manager and MyEnlighten monitoring options, and compatibility with Enphase Envoy-S.

Rated ambient temperature range is -40 °C to 65 °C and relative humidity range is 4% to 100% (condensing), so they are suitable for use pretty much anywhere. RRP is POA as they are usually supplied as part of a solar system.

Contact:

Check website for your closest installer.enphase.com/en-au

Buy refurbished and save

While it’s tempting to buy the latest tech, the fact is that most people simply don’t need the latest and greatest. For the average technology user, refurbished machines make a great alternative to buying new.

The advantages of buying refurbished include a much lower purchase price while repurposing a machine that may otherwise have become e-waste.

Reboot-IT has a range of desktop and laptop computers, tablets, mobile phones, printers and even replacement parts, with models and availability changing constantly. There are some bargains to be had, such as the Acer laptop pictured, which features an i5 3230M 2.6 GHz processor, 4 GB of memory, a 500 GB hard drive and 14” screen. All this, including a valid licence for Windows 7 Pro, is just $219.

There are many similar bargains available, with device condition ranging from almost as-new (A-grade) through to those with a few more knocks and dings (B- and C-grade). A-grade machines usually have a warranty and come with their original accessories, so they can be ideal for low-level or cost-conscious users such as kids or students.

Contact:

Reboot-IT, ph: 1300 747 788 sales@reboot-it.com.aureboot-it.com.au

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P R O D U C T S

What is load shedding?Occasionally a part of the grid (such as a state) has insufficient generation available to supply the total demand for electricity, so there is too much load for the generators to handle. If nothing is done, the overloaded generators will slow down, electrical frequency will drop below specification, equipment will switch off to protect itself and the entire grid could be blacked out.

One way to cope with such an under-supply is to reduce load on the generators by disconnecting or ‘shedding’ part of the grid. Local grid operators define areas subject to load shedding based on parts of their networks supplied via high-power cables called feeders. Just as each circuit breaker in your home’s switchboard supplies a group of appliances, each feeder supplies a group of communities. To minimise inconvenience for electricity consumers, each area is only disconnected for half an hour or so before being reconnected, with another area switched off in turn. The impact rolls from suburb to suburb, leading to the term ‘rolling blackout’.

Load shedding is rare—the grid’s reliability standard equates to 99.998% availability on an energy-served basis, and this has been breached only once in the past 11 years (see Figure 1 and bit.ly/AEMCGR).

How are areas selected for load shedding?Grid operators maintain a list of feeders; once an area has been ‘load-shed’, it’s not likely to be targeted for future load shedding until each other area on the list has had its turn1. In most cases these lists are confidential, but

the current South Australian one is publicly available (bit.ly/SA_MLSL).

SA has 22 groups, each containing many suburb names. According to the list, the most recent load shedding occurred on 8 August 2017 when part of Woodville was shed (in group 9). The next time load shedding is required, it will probably hit Wingfield and parts of Woodville Gardens.

Some electricity feeders are exempted from such lists because they supply important infrastructure such as underground trains, traffic management, emergency services or hospitals. If you live in a nearby area you may be immune to load shedding.

Why can there be insufficient generation?In most states demand for electricity is highest during a heatwave that occurs outside of holiday periods. The critical times tend to be around 4 pm when many businesses are still operating and kids have come home from school, or in the early evening when people return from work. Over millions of premises, air conditioning can become a major load.

The maximum demand for grid electricity varies greatly from year to year depending on how weather conditions align with working hours. It also evolves over time due to changes such as new housing construction, closure of manufacturing and increases in

A R T I C L E

Image: David Tooby.

Large numbers of solar homes can reduce the chance of a scheduled outage. But if load shedding does need to occur, the lower loads from solar homes could mean that the outage needs to be more widespread.

16 issue 147 renew magazine renew.org.au

Load sheddingcoming to your area soon?In recent years several parts of the electricity grid have suffered outages and media discussion of the causes has been intense. Why do such events occur, how are they managed in the grid and how is rooftop solar changing this? Renew’s Andrew Reddaway looks at the issue of load shedding.

Back in 2011 I took the first tentative steps to taking my home off the grid. I detailed some of these in a number of Renew articles starting with issue 119.

Originally, I wired my house with separate 12 V lighting and used 12 V solar PV and a set of lead-acid batteries to power them.

In the following years I built a 12 V solar hot water system, a couple of 24 V solar-powered air coolers and a 24 V solar-powered hydronic room heating system.

Next, I set up an MPP Power PIP4048 5 kW off-grid inverter-charger in my garage connecting 3 kW of west-facing solar PV to 10 kWh of deep-cycle gel lead-acid batteries and had my electrician connect it to additional red power points around the house. This system still runs my fridge, computers and TVs.

In 2017 my mother passed away and I received some money from her estate. I decided this was my chance to invest properly in my home and truly go off-grid with a bigger system.

The new off-grid systemWhen I bought it, my block of land came with a large shed on the back boundary.

My new concept was to cover that shed roof in solar PV and install an off-grid system to power as many of my house loads as possible. A new switchboard would contain a changeover switch that would connect the house to either the shed’s solar system or the grid. This grid connection would provide a final backup if things went wrong and also allow my 10-year-old 3.5 kW solar system to continue exporting to the grid until the 40 cent feed-in tariff expires in a few years.

Choice of batteriesLooking for at least four days of autonomy and preferring to avoid a diesel start in the middle of the night, I calculated that I would need 20 kWh of battery (see Table 1) with a maximum load of around 6 kW.

Initially I looked at LG Chem RESU batteries, but I found that the 10 kWh unit was limited to a 5 kW load even if you daisy chain a few together. So instead I looked at a new entrant to the battery market, BYD. This large Chinese battery company entered the Australian domestic market in 2015 with a new battery cabinet that used 48 V lithium battery modules ‘tried and tested’

for telecommunications use. Each cabinet could accommodate from one to four battery modules, giving a capacity of 2.5 to 10 kWh. A BYD cabinet fully populated with four modules would allow me to draw 10 kW, easily covering my 6 kW requirement.

I decided to install two BYD cabinets for a total of 20 kWh storage and theoretically up to a 20 kW load. Cost per fully populated cabinet was $6500 making a $13,000 total outlay for batteries.

Solar collection The 8.2 kW solar array on the shed consists of 255 W polycrystalline CSUN solar panels

A R T I C L E

The solar panels on the garage feed power to the house via the Selectronic inverter and the battery bank. As you can see, Martin has quite a few small solar energy systems!

36 issue 147 renew magazine renew.org.au

Off-grid in the suburbsMartin Chape tells us about his experiment in taking a suburban house off the grid.

Appliance and lighting upgrades

Jonathan Prendergast has focused his family’s energy efficiency upgrades on energy guzzling appliances and lights, as well as installing solar and monitoring.

Having moved from Melbourne to Sydney’s Sutherland Shire (a warm temperate climate) 10 years ago, Jonathan Prendergast really notices what a difference the more temperate climate makes to his family’s energy efficiency investment decisions. “When you’re heating from April to October, you prioritise insulation, but here we only need heating for six weeks a year,” he says. “When we’re feeling a bit chilly, just as we are starting to think about getting more insulation or doing some draughtproofing, it gets warm again!”

Their three-bedroom 1960s weatherboard house does already have excellent ceiling and some underfloor insulation. The main upgrades Jonathan has done since moving in four years ago are to replace the ageing resistive element hot water service with a heat pump; install a 7.8 kW solar PV system and a 9.8 kWh battery; and address the energy consumption of their 72 (!) halogen downlights. He disconnected ten, replaced the globes of 30 with LEDs, and installed five new high quality full LED units from local startup Absolute D-Light in the most used section of the house for lighting, the kitchen. The energy draw for all lighting has dropped from over 5 kW to around 1.2 kW.

“The hot water system was accounting for around half of our overall daily electricity consumption,” he explains. “When we installed the heat pump our energy use for hot water dropped from 8–10 kWh per day to 2 kWh.”

The solar and batteries have taken the family’s electricity bills into credit, and Jonathan says that rather than spend money on more insulation, it’s an easy decision to use a bit of extra electricity to run their reverse-cycle air conditioner for the short time in winter that they need active heating.

Their daily consumption is around 12 kWh per day year round, rising to 20–30 kWh on winter heating days and the same for about 20 summer cooling days per year.

Adapted to the heat

Cooling, heating and refrigeration are all energy-use issues to tackle in Alice Springs’ semi-arid climate extremes.

In Alice Springs, the recent summer saw their hottest day on record at 45.6 °C and the hottest March day at 43 °C. “It’s definitely trending up,” says Rachel O’Leary, who’s lived there for 12 years. With strings of summer days from 38 °C to 43 °C and overnights not going below the low 20s, it sounds like a hard climate to live in. But you adapt to it, says Rachel, describing the climate as “mostly pleasant.”

Her family’s single-storey, four-bedroom single-brick home stays comfortable up to about 36 °C, with help from cool tiled floors, well-designed eaves on the north and west

and shading from trees. A significant retrofit for efficiency saw them replace their leaking roof with white Colorbond, and they found the house noticeably cooler after that, by as much as a couple of degrees.

C A S E S T U D I E S

Energy efficiency upgrades

A 7.8 kW solar system teamed with a 9.8 kWh battery, plus measures to reduce their energy use, all help ensure Jonathan Prendergast’s Sydney household is a net energy exporter.

A new white Colorbond roof made a significant difference to the internal temperature at Rachel’s Alice Springs home, helping reduce summer cooling needs.

46 issue 147 renew magazine renew.org.au

50 issue 147 renew magazine renew.org.au

Beat the chillsA draught sealing buyers guideAs we head towards winter, draughts can make your home far less comfortable than it should be. Lance Turner looks at options for sealing up your home for a cosier cold season.

It is generally recognised that unwanted draughts in a home make the home perform poorly thermally, compared to a home that is well sealed. With airflows into and out of a home, energy also flows due to the temperature differences between the interior air and the air outdoors. In summer, air flowing into a home can heat it up, while in winter, warm air flowing out of a home is replaced with cold air, cooling the home and making heating work harder (and cost more to run).

There are desirable draughts, which are usually controllable, such as when you open windows at the end of a hot day to vent out accumulated heat, and there are undesirable draughts, which you have no immediate control over. Generally speaking, unwanted draughts can be caused by gaps between building components or around built-in appliances and equipment such as lighting (particularly recessed downlights).

A home’s level of airtightness is rated in the number of air changes per hour that occur when there is a 50 Pa (pascals, a mere 0.007 psi in the old measurements) difference in air pressure between the indoor pressure and that outside. The ultimate sealing standard for homes is the Passive House standard, which allows for no more than 0.6 ACH50 (air changes per hour at a pressure differential of 50 Pa). This is an extremely tight standard, and very few homes meet (or indeed should meet) this standard. In Australia, the average home is more likely to be 20 ACH50 or worse.

So how airtight should your home be? For most homes, to maintain an acceptable level of comfort without requiring excessive heating or cooling (assuming the house is also correctly insulated, orientated and shaded), an airtightness of 5 ACH50 is enough, with

few Australian homes reaching this level. See box for more on testing airtightness.

Why seal gaps?There are many reasons to seal gaps in a building envelope. The first, as mentioned, is to keep conditioned air where it belongs: inside the home. This reduces air conditioning (heating and cooling) energy use and bills, but also reduces other negative effects of excessive air leakage that may not be immediately obvious.

For example, in winter, draughts can reduce the comfort of a home by making you

feel cold, even in a heated home. You may not feel the draughts, but cold air pools at floor level (cold air is denser and hence heavier than warm air) and so can result in cold feet and a general feeling of being cold. This is known as stratification, where differing air temperatures form into layers. This can be particularly noticeable in winter if you have warm air coming from ceiling ducts or high-mounted reverse-cycle air conditioners.

Severe air leakage can even result in noticeable air movement inside the home, such as feeling a cold breeze inside the home when it is cold and windy outside. Wind

The range of gap sealants, and manufacturers, is huge. There is a sealant to do any gap sealing job in any material. Many sealants are low- or zero-VOC, most are paintable and flexible, and many are suitable for outdoor extremes.

B U Y E R S G U I D E

In more airtight houses, an energy recovery ventilation (ERV) system can help provide fresh, drier, clean air without losing valuable heat (or coolth). Jenny has three small ERV systems in her own home, each with an internal vent (left) and an external vent (right).

60 issue 147 renew magazine renew.org.au

Moisture problems in Australian homes are on the increase. In fact, at the Building Physics Forum at the University of Wollongong late last year, it was a hot topic: younger participants were advised to consider a career change or specialisation in mould management to get ahead of the demand!

Moisture problems can impact on aesthetics, but, much more importantly, they can adversely affect the health of a building’s inhabitants. With high internal humidity and moisture accumulating in the building’s structure, cases of ‘sick homes’ with microbial infestations of mould and fungi are on the rise.

Poor moisture management also results in reduced thermal resistance and structural decay. Managing moisture effectively is really important if you want your home to be healthy, energy-efficient and last a long time.

Water vapour the villainWater vapour is invisible and has the mobility of a gas. It travels very rapidly through air gaps in buildings (sadly abundant in typical Australian homes) and much more slowly by permeating through intact building materials such as plasterboard. It can condense—revert to liquid form—in parts of your home that water would not be expected to reach. It is a troublemaker that requires care and thought to manage.

Condensation presents a serious threat to the durability, energy efficiency, health and safety of homes. Unfortunately, it remains a significant risk in Australian homes due to the evolution of our building techniques, the vastly different climates across Australia and confusion about its causes and ways to manage it.

Holistic thinking: houses are complex systemsAirtightness, ventilation, insulation and moisture control all go hand-in-hand and must be considered together when building or renovating homes. Focusing on one, without thinking through the impact on the others, is asking for trouble and just not sensible if the desired outcome is an energy-efficient and healthy home.

The double envelopeWhen thinking about moisture movement through buildings it is important to understand that a modern house generally has a two-envelope structure: internal and external. Both these envelopes play a role in moisture control; changing one without thinking about the other can quickly result in problems.

The external envelope protects the building from the weather and fire, and comprises the roof, exterior walls, sarking or membranes on the exterior side of timber framing and any barriers around the foundations or slab.

The internal envelope is the inside layer: the interior walls, ceilings, and floors. Windows and external doors are part of both envelopes.

The spaces between those two envelopes (inside the walls, the roof space and sub-floor space) are at risk of unseen condensation.

Humans live inside the internal envelope and generate a lot of water vapour from washing, cooking and simply breathing. A family of four can generate 20 kilograms of water vapour per day, inside a home!

F E A T U R E

Condensation managementIt’s important to consider both ventilation and moisture control in order to avoid condensation problems. Jenny Edwards recommends a holistic approach.

Mechanical ventilation with heat recovery (MVHR) is used to deliver reliable ventilation to maintain excellent indoor air quality in occupied buildings. It supplies fresh filtered air into the building and simultaneously extracts damp, stale or contaminated air, without the energy, comfort and noise issues that can arise with open windows. Mechanical ventilation can be thought of as providing continuous fresh air in a controlled manner. That is, you can know exactly how much fresh air you’re getting with mechanical ventilation—unlike when relying upon opening windows. These systems are designed to operate continuously, while consuming very little power (usually less than 40 W).

The Australian Building Codes Board has produced a handbook that provides information on potential contaminants in indoor air, including sources and acceptable levels (bit.ly/ABCB_IAQ, p. 24). In typical homes, these might include CO2 from occupant respiration, gas cooking and unflued gas heaters; particulates such as PM10 and PM2.5 from cooking, tracked in or from carpet degradation; and volatile organic compounds (VOCs) from synthetic products such as carpets and laminates, cleaning products or even cosmetics. There are some generally accepted standards for good indoor air quality and MVHR systems are designed to meet these.

Why would you need an MVHR system?Natural ventilation through open windows and doors isn’t always going to be enough to ensure good indoor air quality, as this is dependent on variables such as window size and location, occupant behaviour, wind speed and temperature.

An important factor to consider is the building airtightness. Typically, Australian buildings have been constructed to a very low level of airtightness (>10 air changes per hour—ACH—at 50 Pa), so ventilation using windows has been supplemented by air leakage.

When you improve airtightness (to improve energy efficiency of the building and reduce moisture build-up in walls and the roof space), planned ventilation becomes more critical. It’s difficult to stipulate an airtightness figure at which MVHR becomes beneficial, due to variables such as local wind speeds and window areas, but a rough rule of thumb is that you should starting considering MVHR if you expect to reach airtightness levels below 5 ACH at 50 Pa, and definitely look to include it if you are targeting lower

levels, such as the Passive House standard of 0.6 ACH at 50 Pa. It is very difficult to integrate effective ducted MVHR systems once construction has started, so this consideration should be part of the design process for a new building or extension.

Does the presence of an MVHR system mean that you need to keep your windows closed at all times? Certainly not. You can open up your house whenever it is comfortable to do so. The reality is that for most locations there are parts of the year where it is too hot, too cold, too noisy, too dusty or too risky to leave your windows open for long periods.

B U Y E R S G U I D E

Image: Zehnder Group

In MVHR systems, air can flow into and out of the home while heat is transferred from one airflow to the other to retain it. This shows a centralised system with the heat exchanger in the centre of the unit.

70 issue 147 renew magazine renew.org.au

MVHR buyers guideAs homes become more airtight, the need for mechanical ventilation grows. Heat recovery systems bring in fresh air with minimal heat loss. Joel Seagren explains how they work and what to look for.

The stained glass window on the south side of the building.

Image: Ferne Millen Photography (www.fernemillen.com)

78 issue 147 renew magazine renew.org.au

In 2015 I began the process of building a small house at the back of my property. I was keen to do this in as environmentally sensitive a way as possible, using local skilled people and reclaimed and locally produced material—both to reduce emissions and be respectful to the Wadawurrung Country we were building on. [Ed note: For a full profile of this house, see Sanctuary 43.]

I worked with a draughtsperson friend, Dan Procházka, who’d initially made the suggestion about building the house. Plans were completed, incorporating the carpenter’s ideas such as building the stairs on site from reclaimed wood. Then it was on to the planning process and site sub-division. The build began 18 months later!

In effect this was a bespoke house: we created many aspects as the project was built. In particular, the two stained glass windows I sourced influenced the design. One became the frosted bathroom window on the west side (the only window on that side, to avoid overheating issues with windows on the west). The other is on the south side and can be seen from the street. It’s a lovely welcoming sight, right ahead of you when you walk in the front door.

But how do you go about making very old windows fit into an energy-efficient new build? As an energy efficiency advisor, I wanted the building to perform as well as possible. Here’s what we did.

My part in the process was mainly to source the windows. I was quickly able to source them using Gumtree. The ones I found

F E A T U R E

Energy-efficient stained glassIt is possible to reuse old materials in a new energy-efficient build. It just takes a bit of planning and finding tradespeople with the right skills. Vicky Grosser explains.

It’s not just electric cars that are making the news; EVs of all types are popping up everywhere. So what can we expect to see in the coming years as transport electrifies and becomes cleaner and quieter?

In the airBoeing recently successfully completed the first test flight of its autonomous electric passenger air vehicle (PAV) prototype, while 2018 saw the qualification of the electric BlackFly VTOL (vertical take-off and landing) aircraft as an ultralight for use in the US. (The BlackFly is now available for sale there; see: www.opener.aero)

In addition, 2018 saw the Pipistrel Alpha Electro all-electric light aircraft become available for sale here in Australia (electro.aero).

On the waterAfter several years of operation, the first all-electric ferries (the Ampere in Norway, launched in 2015, and the Elektra in Finland, launched in 2017), are continuing to rewrite the book on ferry operations. In particular, the Ampere produced data in 2018 to show the all-electric ferry cut emissions by 95% and costs by 80%, all with much lower noise. Latest reports suggest that another 50 have been ordered from their Norwegian manufacturer, Fjellstrand Shipyard, who builds them in conjunction with Siemens and Corvus Energy.

Electric motors for small boats are also becoming a ‘thing’: for example a small ‘picnic’ boat hire business is now operating a fleet of EV hire boats out of Melbourne’s Docklands (goboatmelbourne.com.au) and specialist EV motor suppliers are opening

here offering electric boat motors (e.g. bbelectricboat.com, see Products this issue).

On two (and three) wheelsAustralian manufacturer Fonzarelli has added a third, higher-performance scooter to its moped range in Australia and Australia Post has ordered 1000 three-wheeled electric delivery vehicles for its fleet.

On four wheelsElectric car sales are soaring, while fossil-fuelled internal combustion engine (ICE) vehicle sales around the world dipped in 2018 from their post-GFC peak in 2017. Even sales of plug-in hybrid EVs (PHEVs; these are vehicles which include both an electric motor and an ICE engine but can be plugged in to charge their battery if desired) have declined

as a proportion of overall EV sales; BEVs (battery electric vehicles) are now taking a larger share as battery technology matures, battery production ramps up and prices per kilowatt-hour fall.

In fact, it may well be that the next stage of the EV revolution has begun. Electric vehicles are currently rolling into mainstream showrooms and selling at a pace that the salespeople of ICE vehicles could only wish for. As ICE sales fell in Europe by 0.23%, China by 6% and Australia by 3%, EV sales around the world rose by a staggering 75%. Even Australia, with its dearth of model choices, recorded about a 10% increase in EV sales compared to 2017, seeing around 2700 new EVs hit the road in 2018.

Based on this increase, the world EV fleet (cumulative EV sales giving the total number

A R T I C L E

The Audi e-tron has a range of around 400 km and can be fully charged in just 30 minutes.

Image: Audi

84 issue 147 renew magazine renew.org.au

EVs everywhere, and not just cars!The move to electric transport, in all its forms, is now well under way and 2019 is shaping up to be a very exciting year indeed. Bryce Gaton explains.

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