Category: Blog

The climate change and global warming are real and we need to take responsibility and try to preserve the environment for the coming generations. Therefore, every organization whether it is big or small should have energy efficiency plan in place to reduce its energy consumption and its carbon footprint. Many organizations are willing to do so but they don’t know where to start and what actions they need to take first and what steps they need to follow to achieve sustainable outcome.

We have prepared the following steps to guide any organization in preparing successful energy efficiency plan for sustainable outcome:

  • The first step is to assign an energy manager in the organization. This energy manager can be one of the organization employees who is interested in energy efficiency and energy management. This energy manager should be able to program the air conditioning thermostat, program timers and program computers and copiers for efficient operation. Provide him with training if required. This energy manager should train other staff on how to use the systems and equipment in the organization efficiently.
  • Prepare an energy efficiency policy for the organization and let it signed by the top management so it becomes part of daily activities and to make the staff commit to it.
  • Schedule energy audits, recommissioning and maintenance to the systems and equipment in the organization to make sure they are tuned for the best efficiency. The energy manager should prepare these schedules along with the maintenance staff.
  • Depending on your budget, work with your energy auditor on action plan and set realistic targets and arrange to implement the energy audit recommendations that have short payback period to give higher return on investment.
  • Set a yearly budget to implement energy audit recommendations and use the savings from the previous energy efficiency projects to fund new projects. Utilize the government grants and rebates to finance your energy efficiency projects.
  • Reward the staff who contribute to energy efficiency to encourage other staff to do so.
  • Provide training to the staff on how to use the systems and equipment in the organization in efficient way to reduce the energy consumption and CO2

If you need help in preparing your energy efficiency plan, don’t hesitate to contact AESS.

Solar hot water system is usually one of our recommendations to our clients to save energy and protect the environment. However, most of our clients complaining that the payback period for this system is long and has low return on investment. This is true but if you consider all the benefits of the solar hot water system, you can see that it is worth the investment and it make sense to have it in your property.

As we all know, the solar hot water system reduces the energy consumption and the energy bills because it uses the free energy from the sun, however, the solar hot water system has more benefits than only saving energy, which are listed below:

  • It uses renewable and secure source of energy because it depends on the sun for heating the water.
  • It is a reliable system that provides hot water year round. When the conventional gas or electric water heater is faulty, it will not provide you with any hot water. On contrary, the solar hot water system will provide you hot water whenever there is a sun in the sky.
  • It requires low maintenance because it has less moving parts. It has only circulating pump(s) for the large central system and it has no moving parts at all for the home system.
  • It reduces the maintenance cost compared to the conventional gas/electric water heater because it reduces the run time and the stress on the gas burner/electric element. This leads to longer service life of the system.
  • It protects the property owner from the increase in energy costs because it uses the free energy from the sun.
  • It is supported by the government because it is type of renewable energy and therefore, you might be eligible for government rebates that reduce your capital cost and make it more attractive investment.
  • It reduces your property carbon footprint because it reduces the greenhouse gases emissions.
  • It increases the value of your property.
  • It attracts the tenants to your property.

There are different types of solar collectors that are used in the solar hot water system but the most two popular types are flat plate and evacuated tubes. We always recommend evacuated tubes collectors to our clients even though they are more expensive for the following reasons:

  • Evacuated Tubes have better heat retention capabilities and generally more heat efficient.
  • It is easier for evacuated Tubes to replace one tube if it is damaged and no need to replace the entire collector like the flat plat type.
  • Evacuated Tubes don’t corrode easily.
  • Evacuated Tubes require less space on the roof than flat plate collectors.
  • Evacuated Tubes are lighter than flat plate collectors.
  • Evacuated Tubes work even in cold weather.
  • Evacuated Tubes produce hotter water than flat plate and therefore, produce more energy.

For a comprehensive review of your hot water system and an energy saving advice, don’t hesitate to contact AESS.

Increasing or decreasing the temperature setpoint in the thermostat of the heating and cooling equipment will affect the energy consumption of these equipment. For example, if you increase the temperature setpoint for a ducted heater or decrease it for an air conditioning unit, then the energy consumption of these equipment will decrease because the heat transfer rate between the inside and the outside of the building will also decrease.

That is true but how much you can save energy by adjusting the temperature setpoint in the thermostat. The rule of thumb says that typically by adjusting the temperature setpoint by 1°C as we described above, you will save around 10% of the energy consumption of the heating or cooling unit.

I wanted to verify this rule of thump and therefore, I put it to the test especially during COVID-19 pandemic, where we have been locked down in our homes for long periods of time and therefore, we have now more time to spend with our families and also we have time to do some research and experiments as well.

To verify this rule of thumb, I used the gas ducted heater in my home and I installed three temperature data loggers as follows:

  • Temperature data logger to measure the outdoor temperature with 1 minute interval
  • Temperature data logger next to the ducted heater thermostat to measure the room temperature with 1 minute interval and,
  • Temperature data logger to measure the supply temperature of the ducted heater with 1 minute interval.

The methodology I used to verify this rule of thumb and measure the energy saving of the ducted heater is as below and note that the heater was running 24 hours per day:

  • I set the temperature setpoint in the thermostat of the ducted heater at 20°C for day 1 (9th August, 2020).
  • I set the temperature setpoint in the thermostat of the ducted heater at 22°C for day 2 (10th August, 2020).
  • The data loggers were measuring the temperatures over the period of these two days from 6 am of the first day to 6 am of the third day.
  • I used the heater supply temperature to calculate the time when the heater was running because its supply temperature was high. When the supply temperature was low, this means the heater was off.
  • Because the heater in my home has constant burner and not modulating (i.e. on/off control), then the gas consumption is proportional to the heater running time and the difference in the heater running time in both days will reflect the energy saving due to temperature setpoint adjustment.

The graph below shows the temperatures measured by the three data loggers over the two days period:

We can note the followings from the graph above:

  • The outdoor temperatures in both days are close to each other but in the afternoon the outdoor temperature for day 2 is higher because it was a sunny day while day 1 was mostly cloudy. No wind in both days.
  • The heater supply temperature shows the oscillation pattern, which represents on/off control.
  • We can see that the heater in both days between 2 pm to 6 pm is almost off because the room temperature was above the temperature setpoint due to the warm weather ouside.
  • We can see that the thermostat maintained the room temperature equal to the temperature setpoint for some extent and the data is more consistent between 12 am to 6 am each day.
  • We can see that the heater supply temperature in day 2 is higher than day 1 and this is because the return temperature (i.e. room temperature) is higher.

As we mentioned above, the data is more consistent between 12 am to 6 am each day and this is because during this time, all my family was sleeping and no effect by sun on the home, which make it more accurate to calculate the running time of the heater in this period and then calculate the energy saving percentage between the two days. The table below summarizes the parameters and the heater running time for the two days:

Time Period

Average Outdoor Temperature (°C)

Average Room Temperature (°C)

Heater Running Time (Minutes)

Day 1 from 12 am to 6 am

7.69°C

19.87°C

148

Day 2 from 12 am to 6 am

8.39°C

21.86°C

171

The above table shows that the difference in average room temperature between the two days is 1.99°C and the percentage increase in heater running time for day 2 compared to day 1 is 16%. This is equal to around 8% per 1°C. Note that the average outdoor temperature of day 2 is higher than the average outdoor temperature of day 1 by 0.7°C and if the outdoor temperature in day 2 was equal to the outdoor temperature in day 1, then the percentage might increase to 9% or more.

Based on the above discussion, we conclude in our opinion that the rule of thumb of 10% increase/decrease in energy consumption of the heating and cooling equipment per each 1°C setpoint adjustment is for some extent correct.

Energy Saving Opportunities:

Whenever there is energy monitoring and comfort monitoring in the building, there is always energy saving opportunities identification and improvement. For example, when we look at the graph above and in particular between 10:30 am and 12:00 pm in day 2, we can see that the heater is running for longer time while the room temperature is way more than the temperature setpoint. This is for sure energy wastage and need to be investigated and remedied. What I can say is that during this period of time, my wife was cooking in the kitchen with the stove and the range hood fan were running. This might led to turbulences and cold draught over the thermostat especially it is located close to the outside door. It might not be the optimum location for the thermostat but I learned from this temperature monitoring to turn off my ducted heater during the cooking time to save gas and cut any energy wastage but in the same time maintain the comfort room temperature.

If you are after saving energy in your home or your facility, please don’t hesitate to contact AESS to monitor your energy and comfort temperatures and provide you with ways and solutions to reduce your energy consumption and your energy bills.

If you are planning to build a new commercial building, you should carefully select the air conditioning system because this system consume around 40% of total building energy consumption and over its expected 20 years of service life, its running cost will be substantial. Therefore, you need to select the most efficient system to reduce your energy bills and in the same time get the best return on investment.

To discuss this subject and spread the benefit, we will share with you one of our projects that we completed. In this project, one of our clients engaged us to conduct an energy efficiency design review to one of their aged care facilities in Canberra and they sent us the design drawings and the specifications for this project. We reviewed the design for this facility and we recommended to them many energy conservation measures to include them in the design and modify it accordingly. The annual cost savings from our recommendations was $52,164 with annual energy savings of 1,015 GJ and 234 tonnes CO2 emissions avoidance.  The major recommendation was changing of the air conditioning system from 4-pipe heat recovery chiller to VRV system with heat recovery.

To find out and advise our client on the most efficient air conditioning system for this facility, we analysed three options as listed below. All these systems provide simultaneous cooling and heating:

  • 4-Pipes Hear Recovery Chiller System.
  • Chiller/boiler System.
  • Variable Refrigerant Volume (VRV) System with heat recovery.

We have assumed that the cost of the fan coil units, pipes, valves, controls and the installation labour are the same for all the three options because they are very similar. We considered the cost of the followings in our calculations for each system:

  • For the heat recovery chiller, we have considered the cost of the chiller itself only because the chiller has built-in pumps and pumps VSD.
  • For the chiller/boiler system, we have considered the cost of the chiller, the boiler and the chilled water and hot water pumps and their VSD.
  • For the VRV System, we have considered the cost of the outdoor units and the heat recovery boxes.

The best way to analyse and compare the efficiency of these three options is by using energy simulation software, however, this is was beyond the scope of this project. We used instead the manual calculations with reasonable assumptions and estimations such as the heating and cooling degree days method to give indication about which system is the most efficient to allow our client decide on which system to use for this facility.

The required air conditioning system cooling capacity for this facility was 500 kW and the heating capacity was 560 kW. The table below compares the three options and their annual running cost:

Summary of the Three Options

Budgetary Capital Cost ($)

Annual Energy Cost ($)

Annual Electricity Consumption (kWh)

Annual Gas Consumption (MJ)

Annual Energy Consumption (GJ)

Annual GHG Emissions (Tonnes CO2-e)

Heat Recovery Chiller System

$306,400.00 $114,484.47 618,834.95 2,227.81 513.63

Chiller/Boiler System

$255,500.00 $148,105.27 103,921.26 5,155,193.33 5,529.31 351.23

VRV System

$200,000.00 $71,185.56 384,786.82 1,385.23 319.37

From the above table, we can note the followings:

  • VRV system has the lowest running cost. The running cost of the VRV system is around 62% of the running cost of the heat recovery chiller and 48% of the running cost of the chiller/boiler system
  • VRV system has the lowest capital cost. The capital cost of the VRV system is around 65% of the capital cost of the heat recovery chiller and around 78% of the capital cost of the chiller/boiler system
  • VRV system has the lowest GHG emissions. Although, the chiller/boiler has lower GHG missions than the heat recovery chiller but its running cost is higher. Note that this is true for Canberra because the gas tariff is high but if the project is located in Melbourne for example where the gas tariff is almost half the tariff in Canberra, then the running cost of the chiller/boiler system would be less than the running cost of the recovery chiller.
  • Chiller/boiler system has higher annual energy consumption than the heat recovery chiller but less GHG emissions. The reason for that is the natural gas produces less GHG emissions per MJ compared to the electricity.

Therefore, the total savings in the first year if VRV system is used instead of 4-pipe heat recovery chiller will be $149,698.90.

We further carried out life cycle cost analysis to estimate the present value of the total cost of each option over 20 years, which is the expected service life of all the three options. Our analysis showed that the heat recovery chiller will cost $1,783,908 over 20 year service life, while the chiller/boiler system will cost $2,132,393 and the VRV System will cost only $1,121,026. If the VRV system is used, it will save $662,881 over its entire 20 years service life compared to the specified 4-pipe heat recovery chiller.

Based on the above savings of the VRV system, we recommended to our client reconsidering this system for their facility. We have roughly examined the dimensions of the VRV outdoor units and found that 20 outdoor units with 28 kW nominal cooling capacity each, will fit in the plantroom apace available on the roof. These 20 VRV Units give much better redundancy than only two heat recovery chillers. For example, if one of the heat recovery chillers is faulty or shut down for maintenance, the air conditioning system will lose 50% of its cooling and heating capacities, while if one of the VRV units is faulty, then the air conditioning system will lose only 5% of its capacity.

If you have a building or a facility under design and you need to make sure the design is efficient, then please contact AESS for an energy efficiency design review to make sure your design does not miss any energy conservation opportunity. Obviously, changing the system design on paper is more sense and more cost effective that changing it after the system is installed.

To save energy when we use the systems and equipment in the building, we need to know how these systems operate and how they waste energy. Whether the system is an air conditioning system, hot water system or any other type of system, it should be run efficiently by knowing its principal of operation and how it is controlled.

In most of small to medium buildings there is no facility/building manager resident in the building who should have the technical knowledge and expertise and can understand the operation of these systems and run them efficiently and therefore, this responsibility lay on the building owner and the tenants. We conducted energy audits for a lot of small to medium buildings and in many cases; we found that the users waste energy without knowing they do that. In other cases, we found that some systems and equipment have energy saving functions in their controls but the users did not know about them and they did not use them.

We appreciate that most of the users don’t have that technical knowledge to understand how all the systems in the building operate but the operation principals of these systems can be explained to them in a simple language by an experienced person to help them save energy and reduce their energy bills.

Therefore, what should the building owners and tenants do to better know their building systems and run them more efficiently?

  • Engage a qualified energy auditing company to conduct a comprehensive review for all the systems and equipment in the building and to explain to you how these systems operate and how to use them efficiently. In addition, the energy auditing company will provide you with recommendations for energy conservation measures.
  • Ask your service agent who services your building systems regularly to sit with you for a cup of coffee and explain to you how these systems operate and how you can run them more efficiently.
  • Read the operation manual of these systems when you have time. These manuals usually provide description for the operation of these systems and how to control them. In many cases during our energy audits, we found energy saving functions built-in in the controls of these systems, which can be activated through the user interface but the users did not know about them.

For a comprehensive review and energy audit to your building systems, please contact AESS.

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