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.

You may have come across this news item a couple of months ago but it is worth taking another look. Although, the study was conducted by a major spam-ware corporation, it is clear that junk e-mails have a huge carbon footprint.

(image: www.fotolia.com)

Anything powered by electricity emits greenhouse gases. Recently research was conducted in the US to find out the amount of energy needed to transmit, process and filter spam globally. The results were startling. According to the ‘Carbon Footprint of Spam’ report the average greenhouse gas emission of a single spam message is 0.3 grams of CO2. Is this a lot? Well, if you multiply this by the number of spam sent annually it translates into a huge figure.

It is estimated that there are 62 trillion junk e-mails sent each year. In terms of energy this equals to the energy needed to drive a car around the planet 1.6 million times. If looking at the electricity needed to power these spam it equals to 33 billion kWh. This amount of electricity could power 2.4 million homes for a year! Spam-related emissions for all e-mail users around the world in 2008 totalled 17 million tons of CO2 or about the same as the emissions produced by 3.1 million passenger cars. That’s 0.2% of the total global emissions.

The report found that about 85 to 91% of all e-mails globally is spam. Nearly 80% of the spam-related GHG emissions came from the energy used by the PC users viewing, deleting and searching for legitimate e-mails amongst the junk e-mails. But spam filtering itself accounts for about 16% of spam-related energy use. To view and trash a piece of spam takes about 3 seconds.

If every inbox were protected by spam filters, organisations and individuals could reduce today’s spam energy by 75% or by 25 billion kWh per year. This would save the same amount of greenhouse emissions as produced by 2.3 million cars. In late 2008 a major source of online spam was taken off line and global spam volumes dropped by 70%. However, there are always new ones to take its place.

When your IT equipment is due for upgrade it’s the perfect time to greatly reduce your computing energy use. But how do you know what products to use?

The US EPA Energy Star standard is now the defacto standard for energy use computing equipment. This certifies products as either being energy star compliant or not.

This is now a quite stringent standard, with version 5.0, the latest version, coming into force on 1 July 2009. The standard takes into account the power used by computers when off, in standby mode, and when in idle mode (that is when on, the operating system has loaded, and activity is limited to basic system applications).  Each mode is weighted according to an estimate of the hours per year the computer will be in each mode.

For example to be energy star compliant a category A desktop computer (your typical office computer with a single core processor) would need to use say less than 2 watts when off and in standby mode, and 39 watts or less in idle mode. Most desktops we measure when undertaking audits consume more than these threshold limits. A similar category A notebook would need to use say less than 1 watt in off and standby modes, and 13 watts or less in idle mode.

Thin client requirements are similar to laptop/notebook requirements.

The Energy Star (5.0) standard covers five categories:

1. Desktops, Integrated Desktops and Notebooks
2. Workstations
3. Game Consoles (under development)
4. Small Scale Servers
5. Thin Clients

So a simple way to maximise the energy savings from your next computer upgrade is to specify that ALL equipment (desktops, notebooks, thin clients, servers) be Energy Star (5.0) compliant. Or if your upgrade isn’t happening for a year or so, to the most recent Energy Star version at that time. You can see full details of the standard at the Energy Star website.

And of course if you are currently operating desktop computers seriously consider thin clients (which will cost no more, but greatly reduce your energy use) or notebook computers.

The Energy Star site includes a list of products that are available internationally, and not just in the US.

In conjunction with the Energy Star site you can also use the EPEAT website, which assesses products against a range of sustainability criteria including:

• Materials selection
• Design for end of life
• Product longevity/life cycle extension
• Energy conservation
• End of life management
• Corporate performance
• Packaging

The EPEAT site lists products available in 40 countries, including Australia. It is a program of the Green Electronics Council, a charitable not for profit organisation. EPEAT is a green electronics certification system. The list of EPEAT certified computers in Australia is pretty small, so if you have a preferred vendor who isn’t on this list I’d encourage you to ask your vendor to get their product EPEAT certified.

Computers continue to get more powerful, but are they using less power? This afternoon I interviewed Stuart King from Dell Australia/New Zealand. Stuart talks about how computer power use is coming down, discusses the Intel vPro technology for power management, thin client computing, and how you can greatly reduce computer power use at no cost. Click here to listen to this interview which looks at how computer technology is advancing. This interview is particularly recommended for anyone in the process of upgrading their computers - the perfect time to achieve some big energy savings for your organisation.

The Climate Savers Computing initiative aims to reduce computer energy consumption by 50% by 2010. Organisations on its board of directors include Dell, Google, Intel, HP, Microsoft, CSC and WWF. It has hundreds of members, all committed to purchasing energy-efficient PCs and servers for new IT purchases, and to broadly deploying power management.

The CSC website includes case studies on deployment of aggressive power management across entire organisations, and a range of guides for activating power management settings. It has a large FAQ section, and if you want to learn about power management the chances are you will find an answer on this site.

Use this site to help you promote and roll out effective power management of your existing computers.

If upgrading your computers seriously consider a thin client or virtual desktop solution for maximum power savings, unfortunately the Climate Savers Computing Initiative doesn’t yet have much information on these solutions.