Carbon Conservation & Energy Efficiency


Bruce Rowse & Team

Archive for the ‘Carbon conservation’ Category

How self-limiting beliefs are wasting money and energy

Tuesday, January 26th, 2010

Last year VECCI - the Victorian Employers Chamber of Commerce and Industry – undertook a survey of business attitudes to climate change.

A surprising – and very disappointing result – was that many businesses believed they had done all they could do to minimise their energy use and carbon footprint.

This self-limiting belief means that these businesses are wasting money and energy, and producing greenhouse gases – needlessly.

One of our customers, who has already cut their energy use by up to 40% across a range of facilities, had us do a quick search for further energy saving opportunities late last year. This organisation is well known as being a leader in energy conservation and saving. Were we able to identify further opportunities to reduce their energy use, within their payback period? The answer to that is a resounding YES.

Henry Ford had a great saying which I love to quote. “If you think you can, or you think you can’t, you’re right.”

If you turn all your computers off at the end of the day and don’t leave lights on in empty rooms you might think you are doing all you can to save energy. But that would be wrong. For example, you probably still have opportunity to delamp (remove excess lamps in areas that are too bright), and to save computer power through aggressive power management settings. And that’s without investing any capital! If you have some money to invest you can save any more, and get a return on investment the banks would kill for.

If you want to cut your energy use, you can!

What will make zero net energy office buildings affordable by 2020?

Wednesday, September 16th, 2009

A zero net energy office building is one which consumes no net energy. Its an office that uses very little energy, then has some form of renewable energy to generate all the power it requires.

With current off the shelf solar technology, presuming little or no shading, its possible to get around 100 kWh  of energy per year per square meter of solar panels at latitudes of around 40 degrees, more in sunny locations at lesser lattitude. For a single storey building, with a roof covered with solar panels, and little shading, keeping office energy consumption to 100 kWh/m2 is easy, and in fact I’ve audited quite a few small offices that are nothing special but only use in the order of 100 to 120 kWh/m2. But a grid connect solar system nowdays costs in the vicinity of  $700 to $1,000 per square meter, which is pretty  expensive, so there are very few zero net energy offices in existence.

Aggressive energy conservation and use of off the shelf technology (like skylights) can mean that office energy consumption is kept down to somewhere between 30 to 50 kWh/m2, meaning only half the roof needs to covered with solar panels, or allowing for some shading. For example our office uses only 30 kWh/m2/year, but is shaded in winter, we could make it energy neutral now just by covering around 2/3rds of the roof in solar panels.

So it is possible now, in 2009, to have a zero net energy office, but its not easily affordable, yet. And if your office is 3 storeys or higher, its becomes very hard to achieve no matter what your budget.

Technological advances however, are happening rapidly and I believe that by 2020 a zero net energy low-rise office may be affordable. And importantly this should be achievable by retrofitting an existing office building, with no need to especially construct a new building. Some of these technological changes are:

  • The emergence of LED lighting. Assuming by 2020 we have LED lighting of around 200 lumens per watt. Allowing for some daylighting, and good use of task lighting, it may be possible to have annual lighting use less than 8 kWh/m2/year.
  • Computer efficiency improvements. Assuming that with thin client architecture and high efficiency monitors by 2020 an office PC uses 15 watts, and that a 200 watt server can then serve 30 clients, computer energy use would be around 3 to 4 kWh/m2/year.
  • There are many likely pathways for HVAC, which will depend on climate. A likely pathway for temperate climates is 100% fresh air HVAC systems, with air to air heat exchangers, but also using legacy internal ducting to allow high flow full economy cycles. Fans will be highly efficient, and heat pumps will have high efficiencies at a range of loading conditions, with the conditioning of air separated from ventilation to lower fan energy use. Couple this with light weight retrofit phase change materials (PCM) to provide thermal mass (eg plasterboard with encapsulated PCM), white roofs (where there are no solar panels), glazing treatments and new insulating membrane technologies to improve the thermal performance of the building. Seal the building well, and combine with good use of sensors and intelligent control all of which limits HVAC energy use to say 15 kWh/m2/year.
  • Miscellaneous loads: high efficiency fridge at say 150 kWh/year; near zero standby loss hot water system; high efficiency multi function devices, totalling say 4 kWh/m2/year.

This will result in total office energy use of around 30 kWh/m2/year.

With aggressive energy conservation occupants should be able to to get down to say 15 to 20 kWh/m2/year.

Assume solar panel efficiency is more than double current efficiency and the installed price per watt of a grid connect system is one third of the current cost. This will provide 260 kWh/m2/year at a cost of say $500 per square meter.

A single story unshaded office where aggressive energy conservation is practiced will then need only 8% of its roof covered with solar panels, at a cost per square meter of building area of only $40.

A three storey half shaded office building would need most of its roof covered.

It should be possible to have a 7 storey building energy neutral if unshaded and the roof is covered with solar panels. Of course if additional solar panels can be added to walls it should be possible to get even taller energy neutral buildings.

By 2020 the net zero energy low-rise office building should be easily affordable, and in fact it may well be standard good financial practice to convert existing office buildings to energy neutral ones. So even building owners with no interest in acting to slow climate change will have energy neutral buildings. And most low rise office buildings then - whether they are 100, 50, or 1 year old -  could be energy neutral.

I say “should” and “may” because I still have some doubt as to whether a couple of the technologies that modify the thermal performance of a building –  particularly PCMs, and retrofit membrane’s that improve its insulation properties – will be affordable. But then again with focus a lot can change in 11 years, and as more of us demand better energy performance from our buildings I believe that this will spark the innovation needed to make zero net energy office buildings common place.

You can help make this a reality by acting now to make your building more efficient. Do what is affordable now. Then repeat regularly - technology is now advancing quickly. You’ll create the demand that will drive the innovation that will create the technology that will make energy neutral buildings common place.

Painting your roof white better than a PV system in slowing global warming

Thursday, September 10th, 2009

Lawrence Berkerley National lab reported November last year on some fantastic research into how “cool roofs” can help slow global warming. White surfaces reflect rather than absorb radiation, and can be effective in re-radiating heat back into space. I’ve only just come across this research today, and the potential greenhouse gas savings are enormous.

Painting a roof white

Painting a roof white

Most roofs are dark in colour, the research by Akbari, Menon and Rosenfield calculated the CO2 offset achieved by increasing the solar reflectance of urban surfaces. For a 100 m2 roof making a dark roof white (with a long term solar reflectance of 0.60 or more) will offset around 10 tonnes of CO2 per year.

A 10 tonne saving per 100 m2 is a large saving. In hot climates white roofs also reduce air conditioning loads. So called “cool coloured” surfaces apparently have only half the benefit.

In California its been law since 2005 that flat roofs be painted white. We should have the same laws in Australia, and should also be legislating that sloped roofs should be white, or at least “cool coloured” as has been the case in California since July.

Assuming it costs $1,700 to clean and paint a 100m2 tiled roof white, and thus save 10 tonnes of carbon, this one measure will provide more climate benefit implementing all of the following:

  • Replacing you gas hot water system with a solar hot water heater (gas boosted)
  • Installing a 2 kW solar PV system on your roof
  • And implementing energy conservation measures that save 16 kWh per day

* Assuming an emissions factor of 1 kg CO2/kWh.

If you don’t have an air conditioner “geo engineering” by painting your roof white won’t save you any money. But in terms of tonnes of greenhouse gas saved per dollar invested painting your roof white - whether at home or at work - could be one of the least expensive ways of cutting greenhouse gas emissions. And it may help you avoid the need to get an air conditioner.

If you have a low carbon footprint to start with, based on this research, painting your roof white could actually neutralise your other emissions. And someone with a white roof is doing more to slow global warming than someone with a 5 kW PV system on their dark roof.

Indoor plants make buildings safer

Monday, September 7th, 2009

According to the U.S. Environmental Protection Agency, volatile organic compounds (VOCs) are found in concentrations consistently higher indoors (up to ten times higher) than outdoors. These cause significant health risks. Now scientific research has confirmed that the solution is in many common, easy-care indoor plants.

VOCs include a variety of chemicals, some of which may have short- and long-term adverse health effects. VOCs are emitted by a wide array of products numbering in the thousands. Examples include: paints and lacquers, paint strippers, cleaning supplies, pesticides, building materials and furnishings, office equipment such as copiers and printers, correction fluids and carbonless copy paper, graphics and craft materials including glues and adhesives, permanent markers, and photographic solutions.

Symptoms from VOCs include eye, nose, and throat irritation; headaches, loss of coordination, nausea; damage to liver, kidney, and central nervous system. Some organics can cause cancer in animals; some are suspected or known to cause cancer in humans.  Key signs or symptoms associated with exposure to VOCs include conjunctival irritation, nose and throat discomfort, headache, allergic skin reaction, shortness of breath, declines in serum cholinesterase levels, nausea, vomiting, nosebleed, fatigue and dizziness.

So you could say that these plants are self-regulating air purifiers which also produce oxygen and remove carbon from the air.

As well as adding to our safety, plants add greatly to our comfort. We feel good when we’re around healthy plants because they’re a key part of our natural environment,. To top it off, plants are beautiful, modular and incredibly good value.

So select from those listed below, and google how to care for them, it’s simple. Just be aware that many indoor plants are chosen because they are understorey plants. This means in a forest they shelter under other taller plants, and so often do not cope well with any direct sunlight on them.

These Indoor Plants have been proven to Reduce Air Pollution

Common name Latin name

Parlour Palm Chamaedorea elegans

Dracaena Dracaena marginata and D. “Janet Craig’

Kentia palm Howea forsteriana),

Peace Lilly Spathiphyllum ‘Petite’, Spathiphyllum. ‘Sensation’),

Philodendron ‘Congo’ Philodendron ‘Congo’


Umbrella Tree Schefflera ‘Amate’

Snake Plant /Mother-in-law’s Tongue    Sansevieria trifasciata

Zanzibar Zamioculcas zamiifilia

Sources: Recent Research carried out by the National Interior Plantscape Association and Professor Margaret Burchett at the University of Technology Sydney.

Linfox video on their carbon reduction program

Wednesday, August 12th, 2009

This 8 minute video shows how Linfox is going about reducing its carbon emissions. What stands out for me in this video is the broad commitment across the organisation to cutting greenhouse gas emissions. Use it to help inspire a similar commitment in your organisation.