Carbon Conservation & Energy Efficiency


Bruce Rowse & Team

Archive for the ‘HVAC – heating, ventilation and air-conditioning’ Category

Local climate extremes demand concerted positive action

Tuesday, February 10th, 2009

Black Saturday 7 February 2009: Melbourne’s temperature reached 46.4 degrees (116.5 deg F), fanned by strong hot winds 400 bushfires across the state killed over 170 people and destroyed 700 homes. And the dams supplying the state with water are at record lows.

If letters to the editor in the newspaper are any indication, many people are making the link between the terrible events of 7 February and climate change.

Fifteen years ago – on 21 March 1994 in Rio de Janeiro the United Nations Framework Convention on Climate Change (UNFCCC) came into existence. This document states that “The Parties should take precautionary measures to anticipate, prevent or minimize the causes of climate change and mitigate its adverse effects. Where there are threats of serious or irreversible damage, lack of full scientific certainty should not be used as a reason for postponing such measures.”

Australia’s parliament ratified the convention in 1992 – before it came into force. The USA ratified it in 1992. China ratified it in 1993. 192 countries around the world have ratified the UNFCCC.

Yet fifteen years on global carbon emissions have ballooned. Clearly the parties have NOT undertaken precautionary measures to prevent of minimise the causes of climate change and mitigate its adverse effects.

Based on my understanding of climate change science had there been concerted action to take precautionary measures fifteen years ago Victoria may have still experienced Black Saturday, although perhaps it might not have been quite as bad. This is because of the tremendous inertia in climatic systems. I’d be happy to stand corrected on this by someone suitably qualified.

However if we had managed to cut global carbon emissions from 1994 on I believe that the likely 50 degree temperatures that I have a feeling Victoria may be experiencing in the next twenty or thirty years probably could have been avoided. And that we may well have in our vocabulary then a complete set of Black days – a Black Sunday, a Black Monday, a Black Tuesday, a Black Wednesday, a Black Thursday, a Black Saturday and a Black Sunday.

Unfortunately based on what I read of the science of climate change this full suite of Black days could now well be locked in because of the great inertia of our climatic systems. However if we do manage to greatly cut emissions now we may avoid even worse weather.

Why, in 2009, are atmospheric concentrations of greenhouse gases still on the rise? I believe primarily because of fear of the economic costs that may arise if resources were put into cutting carbon pollution. Fear fanned by fossil fuel dependent industries.

Yet ever since former World Bank chief economist Nicolas Stern published the Stern Review of Climate Change in 2006 its been credibly shown that the future economic consequences of inaction far outweigh the economic costs of acting now to prevent dangerous climate change.

Whoever you are that is reading this – if you are shocked by the events of Black Saturday -  let me put it to you that you should consider cutting your carbon emissions to lessen the number of future black Tuesdays. Don’t just say this is the government’s problem and leave it at that. You see most governments around the world are not doing enough to drive the sorts of carbon cuts we need. The Australian federal government is an example of this – the 5% carbon reduction target by 2020 is laughable given what the science is saying.

So it is up to all of us to do something – both at home and also at work. Don’t just bitch and moan about how the government isn’t doing enough. Do something yourself. Take whatever assistance you can get from your government – but don’t stop at that – go beyond that. People of the world – unite to cut our carbon emissions – hopefully our government’s will one day start to genuinely lead instead of just continuing to play the prisoner’s dilemma.  (That is saying they recognise there is a problem, but aren’t willing to act unless other countries act because acting alone would be bad for the economy and that acting along wouldn’t reduce carbon emissions sufficiently to actually make much of a difference). And if you live in Victoria, make a fire plan.

And let me also suggest that choosing to act may not be of that much economic cost now, that in fact if you are particularly wasteful in your use of fossil fuel sourced energy that you may still be in front financially by cutting your carbon pollution – even after you’ve spend some of your savings to buy 100% greenpower.  And that choosing to act now may well be of great benefit to you and your family in the future.

At home get a smaller car. Then substitute a drive with a phone call, a walk or a cycle. Switch off stuff not in use – at the wall. Insulate. Get rid of those horribly wasteful halogen downlights.

At work do an energy audit, or get one done, and act on it. Delamp. Optimise your cooling and heating. Turn off stuff not in use – at the wall. Get energy efficient computers and equipment.

At home and work buy 100% certified green power, or get solar panels (make sure you aren’t selling the carbon savings in exchange for a discount from the supplier).

Climate change demands a vigorous, positive response – the more of us who do this, the greater the likelihood of climate stability in the future.

How good is T5 fluorescent lighting?

Thursday, January 8th, 2009

T5 fluorescent lighting has been around for a while now, but is not yet widely used in the manufacturing or warehouse sectors. Paul Smith has compared T5s with metal halide, and is interested in how T5s compare in terms of their total environmental impact.

As Paul writes, T5s strike faster, have good colour rendition, and a well designed T5 high bay luminaire, with 4 tubes, can be more efficient than a metal halide lamp, and have less lumen depreciation over its lifetime.

Both metal halide and T5 lamps contain mercury. T5 refers to the diameter of the tube, with T5 tubes being 5/8″ (16mm) in diamater. “Standard” fluorescent tubes are called T8s and are 8/8″ (25mm) in diameter. With a smaller diameter T5s use less glass and mercury than a T8 of comparable brightness.

Having said that, quite a few myths have developed around T5 lamps and as a result many people believe they are the best thing since sliced bread was invented. The luminous efficacy in lumens per watt of good T5 lamps approaches 105 lumens per watt, but this is only slightly better than the best T8 which is near 100 lumens per watt. Large wattage metal halides also have luminious efficiencies approaching 100 lumens per watt. However, like most things, just because a lamp is a T5 doesn’t mean its luminous efficacy is above 100 lumens per watt, there are many T5s on the market with an efficacy of only 80 lumens per watt.

The uptake of T5s has been much greater in the commercial building sector, particularly in offices, than in manufacturing and warehouses. The reason for this I believe is LEED (in Australia Greenstar) and other standards where building designers are seeking maximum efficiency in lighting. These drivers aren’t yet as strong in the manufacturing and warehouse sectors. Certainly in our work we mostly come across T5s in office buildings which are pursuing a high green star rating. And metal halide highbay light fittings are still much cheaper and much more readily available than T5 highbay fittings.

If you are designing a new commercial building it makes economic and environmental sense to use T5 lighting with high efficiency luminaires. The luminaire (light fitting) chosen is important too. The purpose of the luminaire is to direct the light coming out of the tube to where it is needed. Low efficiency luminaires are inefficient at doing this. To get the most out of T5 lighting you also need to be specifying high efficiency luminaires.  A big advantage T5 lights have over conventional T8 is their use of an electronic ballast, which extends lamp life, eliminates flicker, and reduces lumen depreciation.

For a commercial building retrofit the use of high efficiency replacement T8 tube in a double fluorescent luminaire and fitting of a specular reflector behind the tube to increase the efficiency of the luminaire enables the removal of one tube and halves energy use of the fitting. This is called delamping (more at our delamping webite). This provides larger energy and cost savings and is less expensive and more reliable than fitting T5 adaptors – devices than enable a T5 tube to be used in a T8 fitting. T5 tubes fitted with T8 adaptors have a lower luminous efficacy than the best T8 tube, so their use is not advised, not withstanding the marketing hype surrounding T5 adaptors.

In new warehouses in my opinion T5 high bay luminaires as described by Paul are far superior to metal halides. Paul outlines several reasons for this. The instant start of T5s is in many case perhaps the biggest advantage. When undertaking energy audits of warehouses I have usually see the high bay lights running all day, even though different sections of the warehouse will often be empty. This is very wasteful. Unfortunately HID lamps, such as metal halide, high pressure sodium, and the less efficient but inexpensive mercury vapour all take a long time to warm up, and therefore its not practical to switch them off in empty spaces. Forklift operators and staff just aren’t prepared to wait 10 or 15 minutes for the lights to warm up to full brightness.

T5 or T8 linear fluorescent lamps don’t have this problem. So they can be controlled by motion or occupancy sensors. In many cases the hours of operation of lights in warehouses could be reduced from 10 to 12 hours a day to less than 4 hours a day with the use of sensors and T5 high bay fittings. Lighting energy costs can easily be halved.

Another metal halide replacement is the induction lamp, which has the advantage of instant start as well, but can in some cases be retrofitted into the existing high bay fittings. Their luminous efficacy is also pretty good, they are easily dimmed (good where daylighting controls are installed), and prices are coming down. Induction lamps also have a very long lamp life, in the order of 50,000 hours (compared with 14,000 hours for a good metal halide and 20,000 hours for a good T5)

LED lighting is rapidly becoming more efficient, and we have tested LED fluorescent tube replacements achieving over 70 lumens per watt – which is a big improvement over the 40 to 50 lumens/watt we were seeing 12 to 18 months ago. If the luminous efficacy of white LED technology continues to improve this quickly, and prices start to drop, then we may find in five years time that LED is better than all other forms of lighting.

How we have kept our energy use 75% lower than a typical office of our size

Wednesday, January 7th, 2009

This week marks exactly one year since we first moved into our current office of 267 m2. Readings of our electricity meter show energy consumption was 30.2 kWh/m2 for the year. Thats all our energy use – we don’t have a gas connection – and includes heating and cooling of the office. To put this in context, this is lower than any of Australia’s famous green buildings. How have we achieved this?

CarbonetiX office

First, we operate the heating/cooling system manually, and only when needed. Most of the year its off. We get good ventilation through the building by opening the front and back doors. HVAC control

Second, we have delamped – that is removed one lamp from each double fluorescent light fitting, and fitted Mirrorlux reflectors behind the remaining fluoro tube. delamped fluorescent light fitting

Third, we have a good switch off culture. The printer goes off at night. Staff only switch lights on when needed. Computers are unplugged at night time.
printer signage

Fourth, we use laptops, which use less than half the power of desktop computers.

Fifth, we use occupancy sensors to control lighting. If a workspace is empty, the light goes off.

occupancy sensor

Sixth, our internal phone and internet network equipment goes off overnight, using a simple plug in timer. We use VoIP phones with power over network, power over network was chosen deliberately to enable this out of hours shut down.
timer on phone and internal network

Seventh, our servers go off automatically each night after the backup, and are turned on manually the next day.
servers switched on manually

Eighth, in the one office with windows the lights stay off most the time.
daylit office

Ninth- we use a kettle rather than a boiling hot water unit. The boiling hot water unit in the photo has been disconnected.
boiling hot water unit replaced with kettle

Tenth- we have removed the tubes in the outside light of our sign. We don’t operate at night, and there is no need to have it illuminated.
sign with power disconnected

In December last year we installed skylights. As they have only just been installed they wouldn’t have contributed much to our savings last year. But in 2009 they should help keep our energy consumption even lower.

There isn’t a lot of rocket science in what we have done. The biggest savings have come from how we operate the heating and cooling – and we haven’t spent a cent on control systems. Energy conservation is good for the environment, and has saved us money. Assuming the previous tenant used 130 kWh/m2/year (pretty typical for an office this size) last year we saved $4,000 and 35 tonnes of greenhouse gas.

What is a comfortable office temperature (2)

Wednesday, December 10th, 2008

A comfortable office temperature doesn’t depend just on the temperature, there are other factors that come into play. These include the relative humidity, the temperature of surrounding surfaces and the speed of any air movements.

Craig Ryan of Johnson Controls has prompted this second posting with some good observations about humidity and comfort on my first posting on a comfortable office temperature.

The more humid it is, the higher the temperature feels. This is shown in the thermal comfort chart below.

thermal comfort diagram - humidity vs temperature

thermal comfort diagram - humidity vs temperature

In climates which are always hot, or climates that are mostly cold, our bodies acclimatise somewhat to these conditions. The chart above is most appropriate for cooler rather than hot climates.

Moving air makes it feel colder. When its hot creating air movement (eg through fans) can mean that air conditioning systems can be set to provide higher temperatures than would otherwise be the case.

Radiant temperatures of nearby surfaces also make us feel warmer or colder. Because of this sitting next to a large window in winter may still feel cold even though the inside air temperature is 22 degrees Celcius.

By operating heating and cooling systems out to the limits of what is perceived to be a comfortable temperature significant energy and greenhouse gas savings can be achieved. Attention also needs to be paid to air movement and surface radiant temperatures.

What is a comfortable office temperature – and why this is very important when it comes to reducing carbon emissions

Thursday, November 27th, 2008

Changes to temperature settings are a little known but easy way of getting significant carbon savings in offices.

In office buildings the single largest energy user is the heating, cooling and ventilation system. This system will typically account for 40% to 60% of the buildings energy cost and greenhouse gas emissions. A major determinant of how much energy your system uses is the temperature at which it is set to operate. Depending on climate, most offices are set to maintain a year round temperature of either 22OC or 24OC.

Hobsons Bay City Council in Melbourne had temperature settings at the Hobsons Bay Civic Centre adjusted by CarbonetiX engineer Linton Hartfield to allow the temperature to vary between 20 and 25 degrees Celcius. Electricity metering of the air conditioning system showed a 25% energy saving on the packaged heat pump units supplying the building. The air conditioning temperature changes occurred a couple of months after a building extension – which had increased electricity consumption by 10%. According to Environment Officer Rowena Joske, “After the temperature adjustments the electricity bills dropped back to what they were before the extension.” In other words simply adjusting the temperature settings has cut carbon emission by 10%.

Temperature complaints are, however, a major bane to facility managers who can’t seem to keep everyone happy. Do adjustments to temperature settings increase the number of complaints? In the case above more complaints did occur about it getting above 25 degrees in some parts of the building. So the system has been adjusted back in those parts of the building to limit the maximum temperature to no more than 25 degrees.

Comcare, a federal government organisation for public sector employees, has produced guidelines as to what a comfortable office temperature is. According to Comcare the acceptable range of office temperatures is 20 to 26 degrees Celcius, with 20 to 24 degrees recommended in winter and 22 to 26 degrees recommended in summer.

In temperate and cold climates in Australia allowing the temperature in the office to float between 20 to 24 or 25 degrees will significantly cut energy use and carbon emissions as compared to setting the system to maintain exactly 22 degrees. In hotter climates allowing the temperature to go up to 26 degrees instead of making it stay at 24 degrees will similarly save energy and carbon emissions.

For offices in terms of carbon reduction per dollar spent it doesn’t get much better than changing building temperature settings.