The development of the Whole of Home (WoH) process started in 2019, with extensive industry consultation in the formation stages. By and large, the calculation process for Energy usage is pretty similar for the different residential building classes. The NCC now limits the amount of regulated energy a proposed dwelling is calculated to use according to standardised operational assumptions. So, what appliances are now being regulated?

As the Australian Government has regulated the Energy Efficiency of most appliances for several years, most common appliances are already rated for energy efficiency. You can learn more on this at the Australian government’s Energy Rating website.

Which appliances count?

Regulated appliances in WoH cover most high energy-usage equipment:

• Space heating
• Air-conditioning/cooling
• Water heating
• Pool & Spa pumps
• Solar Photovoltaics (PV) (creates an offset for energy usage)

There are two main ways to calculate the Whole of Home energy usage: the ABCB WoH Calculator, and an extension to NatHERS software. The ABCB WoH Calculator is a Deemed-to-Satisfy method & can be applied with either a DtS evaluation of building Thermal Performance, or with a NatHERS assessment of building thermal performance. The ABCB Whole of Home calculator automates the NCC Whole of Home energy usage requirements with extensive look-up tables of performance factors (Part 13.6 of the ABCB Housing Provisions and J3D14 of NCC Volume One). Dwellings smaller than 10m² or larger than 500m² can’t use the DtS calculator.

A house needs to reach 7 stars or equivalent before we can calculate the WoH. Using the DtS WoH method, the building must comply with the Thermal Performance Requirement separately. With the NatHERS WoH calculation, a high-performing building will get recognition in the WoH calculation, because of the reduced need for artificial heating and cooling. There’s also many more options available in the NatHERS WoH assessment, including more accurate efficiency of appliances, solar PV panels, batteries, the type of stove & oven, as well as lighting efficiency.

Meanwhile, there’s some limitations to DtS WoH method: Solar batteries can be counted only in NatHERS software because the software is needed to calculate their hourly impact. Artificial lighting can be counted in NatHERS software, where the average is less than 5W/m². Stoves & ovens can be counted in NatHERS software which estimates costs, energy use & emissions. Plug-loads are not regulated; an average allowance is based on the total floor area (measured inside the external walls and including any conditioned garage).

There’s no way around it – big houses use more energy. Even with high efficiency air-conditioning and water heating, large dwellings will more likely need solar PV to meet the requirements.
The energy usage allowance is related to the societal cost of energy, related to the cost of electricity (or gas) and emissions from generation (not just use).

Unless we’re supplied a detailed list of proposed appliances, we have to use low-efficiency default appliances. So it’s almost always in your best interests to include the air-conditioning, water heating and solar PV details. Pools will likely need solar PV to offset the additional energy usage from pool pumps.

If you still want to know more or have any questions, contact us for more information about Whole of Home. We have an additional Whole of Home Checklist that can help us get the right information for your project. The appliance list is most important (Manufacturer & Model No.) so we can look up the appliance efficiency, however it can vary according to location. If needed, we’ll get you to clarify what you are planning to use.

At Anderson Energy Efficiency, we’ve got you covered for all the latest developments of the National Construction Code.

The post Residential Whole of Home appeared first on Anderson Energy Efficiency.

Building Application is just around the corner and the council has given you a list of forms to obtain to ensure your project complies with the National Construction Code (NCC). Energy efficiency compliance is on that list, but “does my building really need an energy efficiency assessment”?
According to the NCC, all new buildings and extensions must meet energy efficiency standards. However, it’s not always straightforward what requires Section J compliance.
Keep reading as we cover the common building scenarios that will and won’t require an energy efficiency assessment.

When is an Energy Efficiency Assessment required?

There are a few instances when you will need your building assessed for energy efficiency.

• Building application – Every new building must go through building application, and in most cases will require a Form 15 (for commercial buildings and residential buildings using Deemed-to-Satisfy) or a Universal Certificate (for residential buildings using Star Rating) to pass.
• Increasing floor area – Any additions to habitable spaces, such as adding an extension or enlarging a room, will trigger the need for energy efficiency assessment.
• Converting a non-habitable space to a habitable space – For example, fitting out a storage shed with an office, transforming a balcony into a bedroom, or converting the sun-room into an open plan living space.
• Changing building classification for whole or part of the building – For instance, changing an office into a retail space (class 5 to class 6), or converting a garage into a bedroom (class 10a to class 1a).
• Moving/relocating a building – Relocating a building requires assessment due to various factors, such as changes in climate zones and orientation.
• Replacing a roof on an existing habitable space

When you might not need an Energy Efficiency Assessment?

Always consult your building certifier if an assessment is required, but there are instances where it may not be necessary.
For example, swapping existing building elements with elements of the same type may not trigger an energy efficiency assessment. Certain changes may impact the whole building’s operational energy consumption but are not significant enough changes to warrant an assessment.
Examples of these changes are:

• Changing roof or wall colours
• Changing floor coverings (note that changing from wooden floors to carpet may change the outcome of a Star Rating)
• Changing window coverings (e.g. blinds, curtains and awnings)
• Tinting windows
• Exchanging glazing of the same size (changing from lower spec to higher spec – changing higher to lower spec may require assessment)
• Improving shade
• Swapping room use (e.g., converting a bedroom to a study – as mentioned above, converting non-habitable to habitable requires assessment)
• Adding insulation (without modifying the building design to accommodate insulation)
• Adding solar panels
• Building a shed

When does a temperature-controlled space require an Energy Efficiency Assessment?

To understand what a temperature-controlled space is, let’s take a look at the related definitions provided by the NCC.

What is a “Conditioned Space”?

In Volume 1, the NCC defines “conditioned space” as a space within a building where the environment is likely (by the intended use of the space) to have its temperature controlled by air-conditioning. This includes a ceiling or under-floor supply air plenum or return air plenum.
Similarly, Volume 2 of the NCC defines a “conditioned space” as a space within a building that is heated or cooled by the building’s domestic services. However, this excludes non-habitable rooms with heaters not exceeding a capacity of 1.2 kW or 4.3 MJ/hour.

What is “Air-Conditioning”?

As per Volume 1 of the NCC, “air-conditioning” refers to a service that actively cools or heats the air within a space. However, it does not include a service that directly
(a) cools or heats cold or hot rooms; or
(b) maintains specialised conditions for equipment or processes, where this is the main use of the service.

So what does this mean for temperature controlled spaces?

If the main use of indoor temperature control is to maintain temperature or humidity for a product, process or equipment, then the air-conditioning is considered a “service”.
This can include humidity control to reduce condensation risk on cool internal surfaces. The humidity is set to such a low level that the long-term human use of the space may be detrimental to health.
Another example is when the temperature and/or humidity is controlled to promote growth of a product or minimise product degradation.
The aim of an energy efficiency assessment is to assess a building for human comfort. Although a building or a room may be conditioned it may not need an assessment depending on its intended use. If the space is not primarily meant for accommodating humans, an assessment is not necessary.

Conclusion

Determining whether you need an energy efficiency assessment or not depends on the nature of your project. If you’re building a brand new building, an assessment for compliance is generally required. Additionally most renovations, refurbishments, or fit-outs will also need an assessment, with the depth of the assessment varying based on the extent of planned works.

If you’re looking to chat further about this article, or seeking professional advice and expertise for an energy efficiency assessment, contact us for a free quote!

The post Does My Building Need To Be Assessed for Energy Efficiency? appeared first on Anderson Energy Efficiency.

“If the NatHERS Star Rating scale goes to 10 Stars, how can someone design a 10 Star house?”.

Although the National Construction Code requires houses to have a minimum 6 Star rating using NatHERS, there are still demands for a higher performing house. NCC2022 has increased the house Star Rating stringency to 7 Stars NatHERS.

So we decided to accept the challenge with a difficult climate (Brisbane). Additionally, we wanted to see if it was possible to design a 10 Star house, using standard construction materials and techniques (representing the lower construction cost options).

Note: all modelling was done using an older version of BERS, where “10 Stars” was a theoretical limit. Results will vary with the NCC2022 version of NatHERS software. The star bands have been adjusted to make it easier to get 10 Stars. In NCC2022 the “10 Stars” total energy level was found by thermally-modelling a real building (with high thermal performance).

Can you get a 10 Star house?

The simple answer is: yes. We present our rough floor plan (image from BERS Pro) with the following design features:

• 4 Bedrooms (blue), 2 Bathrooms (green), 2 Garages (brown)
• Large Bedrooms flanking the small Kitchen/Dining/Living area (pink)
• Garages and Bathrooms on the East and West short axis (10m)

The floor plan needs more work to make the design practical, but as it stands this is just a design concept for discussion. We are not building designers, we are professional Energy Efficiency consultants.

Floor plan concept for 10 Star house in Brisbane – (Road & North are up; heavy grid-lines are one metre)

The climate we selected was Brisbane – this is one of three climates (out of 69) with the lowest NatHERS total energy that achieves 6 Stars. The mild climate in Brisbane is accounted for and less artificial heating and cooling is expected for other climates using the same design.

To achieve 10 Stars in Brisbane, you need a total energy usage less than 10MJ/m², compared to a 6 Star home which requires total energy usage less than 43MJ/m². A 6 star house with 200m² of conditioned floor area would have an annual electricity consumption of about 185kWh to run air-conditioning for a whole year. This is according to NatHERS thermostat and occupancy (24/7) settings, and with an air-conditioner Energy Efficiency Ratio of 3.0. You can check the energy rating of an air conditioner here.

Specifications

Summary technical specifications for the 10 star house were:

The areas in the brackets are adjusted for wall thickness

The specifications of construction materials, insulation and glazing were modest. This included the ratio of total glazing area to floor area of 18.4%.

In order to achieve 10 Stars other design features were:

• North and South eaves 1.0m, 0.0m offset to glazing head height
• 1200mm ceiling fans to each Bedroom and two in Dining/Living
• Roof medium colour, Solar Absorptance 0.5
• External Walls medium colour, Solar Absorptance 0.5

Results

Using BERS Version 4.4 and the NatHERS Technical Note procedure produced the following results:

Colours represent different rooms

Most of the following changes would make the energy rating lower. By how much—depends on how far you deviate from the 10 Star design:

• Floor area is smaller
• Smaller Bedrooms and larger Living area
• Two stories, or split-level
• Different orientation (e.g. road to East or West)
• Larger glazing
• Less cross ventilation
• Carpet on floor
• Suspended, lightweight floor
• No ceiling fans

These changes may not make a much of a difference:

• Floor area is larger
• Tiles on floor
• Darker or lighter external walls
• Modest overshadowing from adjacent structures
• Darker or lighter roof
• Lower or higher roof pitch
• Skillion or gable roof
• Roof tiles

Sharing external walls (as seen in duplexes, townhouses or units) can improve the Energy Rating because there is less surface area for unwanted heat transfer. Adding shade or overshadowing will reduce summer overheating (increasing cooling energy) but will increase winter over-cooling (increasing heating energy).

The Energy Rating can be improved with attention to glazing sizes, orientation, glazing Uw-value and SHGCw (w = glass + frame), and some shade. Therefore, it should be possible to vary the design somewhat and adjust the glazing in order to retain 10 Stars.

Conclusion

It is possible to achieve a 10 Star house in Brisbane and have a fairly “normal” looking house (from the outside) using standard construction materials and techniques, but it calls for an unconventional floor plan. This design was only assessed in one climate zone, compared to 69 climates zones across Australia, so this design may not work in a cooler climate.

Ultimately, the design and the arrangement of the rooms is what determines if a house made from conventional construction materials will be energy efficient.

If you would like to know what works in different climates, or if you would like to discuss the design further, feel free to contact us to have a chat, or if you’re looking for a NatHERS Star Rating for your house, you can shoot us an email at info@andersonenergy.com.au.

The post How to get a 10 Star house in Brisbane appeared first on Anderson Energy Efficiency.

The Ecological Footprint of each person varies from country to country. Even more so varying per person. The Ecological Footprint is averaged from each resident and this helps countries to improve their sustainability and well-being. Though what has it got do do with Earth Overshoot day?

There are two parts in calculating the Ecological Footprint: the demand on nature and the supply of nature:

• Demand includes the consumption of natural resources and the amount of forests able to absorb its waste, particularly carbon emissions.
• Supply represents the productivity from land and sea sources.

When a populations demand on resources is greater than that region’s biocapacity, there is a deficit. The region will meet it’s demand through importing supply or liquidating ecological assets to sustain itself, however on a global level there are no additional supply to import from off world.

So when is the date?

This, as the Global Footprint Network calculates, is our world’s Ecological Footprint, and is expressed in two ways. The first through global hectares (gha) per person and the second is how many Earths are needed to meet our demand.

At Global Footprint Network, they calculate how long it takes humanity to use up the amount of supply 1 Earth can generate in a year. This is represented as a date where we go ‘over the budget’ and called Earth Overshoot Day. This day has been getting earlier from December 29 each year since the 1970’s, mainly due to population growth. However, with the goal being #MoveTheDate we can slow this down.

In 2017, Earth Overshoot Day was the 1st of August. In 2019, it was the 29th of July.

And in 2020, it’s the 22nd of August.

This improvement is related to the coronavirus pandemic from this year. However this still means we have a third of the year to go. Subsequently overdrawing on our ecological assets.

At Anderson Energy Efficiency our Purpose Statement is:

Helping to reduce the carbon footprint of buildings

Through our experience in Building Energy Efficiency Assessments, we assist clients to not only achieve Code Compliance, but a building that is more sustainable and helps reduce demand on our Earth’s supply.

We owe it to future generations to do our best to minimise our Ecological Footprint, so they can have the opportunity to enjoy earths resources like we have today.

If you’d like to know how your personal Ecological Footprint compares, try this quick quiz to estimate how many Earth’s you would use: https://www.footprintcalculator.org/

The post Earth Overshoot Day 2020 appeared first on Anderson Energy Efficiency.

Since the changes this year in NCC2019 are substantial, to help assist clients & construction industry professionals in this transition we’ve made a presentation that covers the main points of the changes. Presented by our Executive Director, Dr Clyde Anderson, it focuses on the proposed Energy Efficiency changes for the National Construction Code 2019. It covers where we currently are in this transition, the changes to Residential buildings in Volume 2, followed by the changes to Commercial buildings in Volume 1. The presentation isn’t just listing off the raw changes though, Dr Anderson goes into how this will impact your work and how to modify your designs to be more likely to comply with the latest requirements.

(YouTube link if the above video doesn’t work for you)

Additionally, for professionals wanting to test their knowledge of the NCC changes, we’ve put together a short quiz that offers 1 Formal CPD Point & Certificate upon successful completion. The quiz has been designed according to the requirements of the Board of Architects of Queensland. You can download a copy of the quiz here; we recommend answering it while you watch the presentation.

If you wish to receive a formal CPD Point, email us a copy of your completed quiz so we can mark it. A formal CPD Certificate can be issued for an investment of $33 (including GST).

The post NCC2019 Changes Video Presentation appeared first on Anderson Energy Efficiency.

We all experience the world differently, and no one solution will fit everyone – I’m sure you know someone that has no problem wearing just a t-shirt & shorts in Winter or someone who still wears a jacket during Summer. This becomes an issue when you’re an Architect or Engineer trying to create a building that will be used by a variety of different people, all with different needs and expectations. It’s a problem for many different aspects of building design, but here we’re just going to address thermal comfort and how we ascertain that a building’s thermal performance will be comfortable for as many people as possible. The method used to calculate human comfort is called the “Predicted Mean Vote”, or PMV, which is derived from ANSI/ASHRAE Standard 55. This refers to the Predicted Mean Vote of the thermal comfort as perceived by the building occupants.

Over many years in different experiments, thousands of people from varied sample groups have been tested at different environmental conditions to “vote” on how they feel. From these experiments, the analysis of trends and correlations have resulted in the PMV calculation formula.

PMV is an index that predicts the mean vote of a large group of people, represented as a 7-point thermal sensation scale.

A PMV between -1 and +1 means a maximum of 26% of people will be dissatisfied. In fact, a perfect PMV of 0.0 still means 5% of people will be dissatisfied, because some people are naturally more extremely “hot blooded” or “cold blooded”.

How does a building comply with the Predicted Mean Vote Requirement?

In NCC2019 Volume 1, in all three Verification Methods JV1, JV2 and JV3, the PMV must be calculated. In the building thermal simulation the PMV is determined for every occupied building zone/room for every single hour for a whole year. A building should have its results listed in a table that clearly says all the occupied zones, the zone floor areas, and the percentage hours of operation that zone has a PMV between -1 and +1.

Each zone is considered within its individual compliance range when the PMV is between -1 and 1 for more than 98% of the occupied hours. Finally, for a Building PMV Compliance “Pass”, the floor area of occupied zones that comply must be not be less than 95% of all occupied zones. If this is all a bit confusing for you, worry not – we’ll be showing you an example table further down below. But before we get there, let’s go through the actual parameters used in the PMV calculation itself.

Parameters affecting Predicted Mean Vote

Air Speed (unit: m/s, range: 0 to 2)
The speed of air circulating throughout the building space, in metres per second (m/s). If you want to know more on this, we have a handy article on how ceiling fans work with more information on the effects of air speed on comfort.

Air Temperature (unit: °C, range: 10 to 30)
The internal air temperature in a building space in degrees Celsius. It is measured as “Dry Bulb Temperature”, which is the measurement of true thermal air temperature, without influence from humidity or direct sunlight or reflected ambient radiant surfaces.

Mean Radiant Temperature (unit: °C, range: 10 to 40)
The average amount of heat that is radiated into the building from surfaces such as ceilings, windows and walls. This is most often heat that is absorbed and re-radiated by the building fabric into the living spaces.

Relative Humidity (unit: %, range: 0 to 100)
This refers to how much moisture vapour is in the air, expressed as a percentage of the maximum amount of moisture the air can hold at the current temperature, before it is released as condensation or precipitation. That is, the Absolute Humidity (grams per meter cubed (g/m³) of moisture) divided by the Saturation Humidity (e.g. 30g/m³ at 30 degrees Celsius), multiplied by 100 to give the Relative Humidity percentage (%).

Activity (unit: met, range: 0.8 to 4.0)
Activity rate combines two factors: metabolic rate and external work. Metabolic rate is the rate at which energy is produced by the body. External work is the amount of activity being performed by a person, therefore knowing the expected use of a building is important to find the correct activity rate. For instance, 1 metabolic unit (1 met) is about normal for an active seated person in an office. 1.5 met is typical for a standing person.

Clothing (unit: clo, range: 0 to 3)
The amount and type of clothing as well as the ratio of exposed/unexposed skin areas. This affects the rate of heat loss by the body. For example, 0.25 clo would be a T-shirt, shorts, shoes and socks, and 1.0 clo would be a light business suit with shoes and socks. For comparison, 1.0 clo is the value used in NatHERS Home Energy Efficiency assessments.

Using Predicted Mean Vote to determine human thermal comfort

It’s about time for a graph! What would be the air temperature needed to achieve equivalent human thermal comfort with varying air speed and clothing values? Lets use:

• PMV locked at 0.0, representing the mean of the population
• Air Speed on the x-axis of the graph
• Air Temperature on the y-axis of the graph
• Radiant Temperature equal to the Air Temperature (the building’s walls/ceilings are the same temperature as the ambient air)
• 50% Relative Humidity
• Activity Rate set to 1.5 met (a standing person)
• Over four levels of clothing: 1.0, 0.65, 0.4 and 0.25 clo

The result is a series of four nearly parallel curves, with each coloured curve for different levels of clothing. This quantifies the well-known effect of increasing airflow from breezes allowing satisfactory comfort at higher air temperatures. As expected, with more clothing the air temperature needs to be reduced for equivalent human thermal comfort. Interestingly, the curves also show the cooling effect airspeed has on comfort perception as the temperature increases.

The air temperature tolerance is increased by 3.5°C for 1.0 clo by increasing Airflow from still air to 2.0 m/s. This means there’s a certain degree of substitution possible between Clothing and Air Speed. So, when it’s not possible to vary Clothing greatly, Air Velocity can produce most of the desired cooling effect for the same level of thermal comfort… Or in other words, a ceiling fan can make up for situations where you have to wear warmer “smart” business clothing!

Less Clothing improves the tolerance to higher temperatures, but with diminishing effectiveness. For example in still air:

• reducing from 1.0 clo to 0.65 clo (35% less) allows 2.6°C increase
• a further reduction to 0.4 clo (~38% lower) allows a further 1.9°C increase
• and a final reduction to 0.25 clo (~38% lower) allows another increase of 1.1°C in air Temperature

The curves would be similar in shape at other Relative Humidity and Activity Rates with a shift in temperature. Higher Relative Humidity and Activity reduces the Air Temperature for equivalent human thermal comfort.

What my Assessment Report should include

Finally, the actual paperwork part. Your Building Energy Efficiency Assessor must use software that automatically calculates PMV over the simulation year. Therefore, depending on the software used, this should produce a Thermal Comfort Report similar to below (though the Compliance Report should show “PASS”). Knowing how to use the software correctly is of course a requirement, but that’s a complex topic far beyond a couple paragraphs at the end of a related article. Because of this, we recommend using only accredited, certified Assessors.

A table similar to the one shown is needed to confirm Building PMV Compliance. Otherwise, the Energy Efficiency Certification is incomplete as the calculation has not demonstrated compliance with the PMV requirement. In this case, we suggest you return your Energy Efficiency Report to the Assessor for amendment to include all the necessary data. It should go without saying, but all of our Energy Efficiency Reports that require Building PMV Compliance come with a table listing the specific results of your building.

Contact us for a Free Fee Proposal for your next Project!

The post How To Quantify Comfort with PMV appeared first on Anderson Energy Efficiency.

A client came to us with a difficult challenge, their house had the maximum glazing. Roughly 90% of the external façade of their house was composed of double glazed glass. Despite being double glazed, the Solar Hear Gain Co-efficient value of the glazing was high. This meant that large amounts of solar heat was being radiated into the building from each orientation. Hence, large amounts of cooling energy was required in order to maintain thermal comfort.

The client wanted us to achieve a 6 Star Rating for their house (without using credits such as solar panels, complying outdoor living area etc.). Additionally, they did not wish to change or reduce the proposed glazing at all.

Energy efficiency may appear to be a straight forward process. However, there are times when one comes across a project that presents a healthy challenge, for even the most experienced professionals. Though the design faced several compliance challenges, with the help of our expertise, our client successfully overcame them all.

How did we help our client? Read the full case study:
The Maximum Glazing House

Anderson Energy Efficiency provided energy efficiency assessment & consulting for this “high glazing” project. Including issuing a From 15 and Universal certificate (mandatory) required for Building Approval. The assessment was carried out using the NatHERS Star Rating method, which allowed us to observe how the proposed building elements impact the thermal performance of the house.

The post The Maximum Glazing House – A Case Study appeared first on Anderson Energy Efficiency.

When we ask, “Other than price, were there other factors that guided your decision?”, we often hear “No, the other company gave a competitive price for the same thing”. Though the client may not realise what “the same thing” means, this is a classic example of how the feeling of “saving money” powers a decision.
The final decision is ruled by how one “feels” about the information one receives. That decision is then justified by logic.

So, if we told you that we can estimate a clear dollar figure (at our fee proposal stage), of how much we can potentially help you save on construction costs, how would you feel? Would that figure (of how much you can potentially save) be of interest to you and your client?

A few days back, one of our clients told us that the dollar estimate would help convince their economic buyer about our competent services. He said that on their recent project, our Consulting helped them save “approximately $100,000 dollars” in construction costs. He further mentioned that this saving was achieved with our Verification Method JV3 Assessment, and it is a “no-brainer” to spend slightly more on JV3 in order to save hundreds and thousands during construction (compared to ‘inexpensive ‘ Deemed to Satisfy method, which can induce higher construction costs due to its various insulation and glazing stringencies). Now, which consultant will they choose, every time they think of “saving money”?

Will they feel pinched spending $2000 upfront for a JV3 assessment to save $100,000 in construction? Or will they save on DtS (half of JV3 costs) upfront, and end up spending $100,000 extra on construction?

If you would like to know more about how to choose the right consultant, contact us and we’ll send you a free PDF copy of “How to Select an Energy Efficiency Assessor”.

The post Choosing “cheap” consultants: Saving Money or Increasing your Construction Costs?! appeared first on Anderson Energy Efficiency.

It may be easier to consider the way more Sustainable Buildings will become reality. We can only achieve Sustainable Buildings incrementally, with small “course correction” moves that can steer us closer.

Driving a car, you are constantly moving the steering wheel to stay on the road. We know that fixing the steering wheel is not safe, even on a straight road. With continuous course-correction we can reach our destination safely.

In the sustainable buildings space, there are many examples of doing “it” better. The annual ‘Sustainable House Day’ provides many examples in a more accessible fashion.

There are several obstacles to achieving “truly” sustainable buildings. What causes buildings to be less sustainable? Is it always cost? Do we give cost more importance than is eventually warranted? That is, over the whole time that a building is used, how does the total lifetime benefits of something compare with the incremental extra cost?

For elements of sustainable buildings this benefit-cost exercise can be calculated. How can we know if something is “worth it”? What do we include and exclude in the calculations? What assumptions and data do we use?

Is a solar PV system more sustainable?

For example, a potential component of sustainable buildings is solar PV. The first question to ask is: Does adding solar PV bring the building closer or further away from being sustainable?

Now we could try to define “sustainability”, but inherently the word implies the ability to “stay”, to keep doing something nearly forever, with neutral impact. Moreover, the question we can ask: is this topic clearly seen as part of a desirable future? With less of the “bad” things, and more of the “good” things (like clean air, clean and adequate water, adequate and durable building materials, etc.)? Is there a straightforward, ongoing process of upkeep and maintenance? At the end of it’s useful life, can the item be upgraded or recycled?

So back to solar PV, in many respects the ability to generate electricity from sunlight is “magical”. However the reality is: the process involves several complex parts to work together. If one of these parts stops working, then the PV system stops working. The only way for solar PV to be sustainable is by ongoing maintenance. So long as the spare or replacement parts and expertise remain available, the solar PV system should be able to last as long as the building.

What is the lifetime cost of solar PV? What is the lifetime benefit? kWh electricity generated, avoided grid power cost saving, reduced impact from generating mains electricity, and even shading of the roof by the solar panels. The answers depend on the situation. Is it a “no-brainer”, or is there more to consider?

Buildings are more sustainable now

Sustainable buildings may not include all the parts of current building design. But the good thing is that today we are building more sustainable buildings than in the past. This is partly due to Sustainable Buildings being part of the National Construction Code, and improved construction materials and practices.

We are already on the journey of Sustainable Buildings!

Anderson Energy Efficiency’s Vision Statement is:

Advancing Sustainable Buildings across Australia

In summary, this is the journey that we are on. If you think this goal is necessary and desirable, come and join us to help make this happen. The only way to achieve sustainable buildings is to stay on the journey, incrementally – by choosing better ways; one project at a time, and one decision at a time.

The post Sustainable Buildings as a Journey appeared first on Anderson Energy Efficiency.

1. Star Ratings Differ

When talking about NatHERS Star Ratings, the first thing to realise is that Star Ratings are mainly for comparing designs in the same climate. This means that if you are in a different climate, the amount of energy to achieve the same Star Rating will be different. The energy calculated is only for heating and cooling; nothing else. The units of energy used are MJ/m² which means larger houses use more energy to achieve the same Star Rating as a smaller house.

The table below is a summary from the NatHERS Software Accreditation Protocol, which determines the accuracy of the Star Rating software. The first column is the building’s location. The second column indicates that location’s climate zone. There is a total of 69 different climate zones that cover all of Australia in the current NatHERS software. The third column details the energy (MJ/m²) numbers required for a 6 Star building. These numbers relate only to the climates/locations listed, other nearby climates will have different MJ/m² numbers. There is roughly a 10:1 range between the highest – lowest energy number for “6 Stars” across all NatHERS climate zones.

2. Home Sizes and Uses Vary

The final column in the table above is an estimate of electricity used for heating and cooling only. Other uses of electricity (refrigeration, lighting, water heating, cooking etc.) are not included. Energy for these other uses greatly varies, depending on type and size equipment and how it is used. For example, one assumption made is that the thermostat settings for heating and cooling in the NatHERS calculation is similar to an actual home. In reality, there will always be differences (plus and minus).

If the home is constantly occupied throughout the day by temperature-sensitive people (such as small children or the elderly), the assumed thermostat settings may be similar. However, this assumption may be inexact for people who can tolerate cooler indoor temperatures in Winter and warmer temperatures in Summer (thus using the air-conditioning less often and having lower energy consumption).

We have also assumed the efficiency of the ducted, reverse-cycle air-conditioning unit (Coefficient of Performance and Energy Efficiency Ratio) is 3.0. (3.6MJ = 1kWh thermal = 1/3kWh electrical). The 200m² home may have several non-conditioned spaces, (such as a garage & outdoor living areas) that are not included in the calculations. A larger (or smaller) home, with a lower (or higher) efficiency air-conditioner will have proportionately different kWh numbers for indoor climate control.

Typically, the Coefficient of Performance for heating is higher than the Energy Efficiency Ratio for cooling. Both of these numbers refer to the ratio of heating or cooling delivered, divided by the amount of input electric energy. To split the result between heating and cooling requires more information about how the building is performing over a year. This information can be found from an Energy Rating Report or a NatHERS Universal Certificate.

3. Energy Costs Differ

There are a range of domestic tariffs available from different suppliers in each city. The rates vary depending on the type of account and metering arrangement. Have a look at your electricity account and find the energy charge in c/kWh (or $/kWh). On the electricity account there will be other fees or charges, per day or per bill, which are not energy-related.

Table below shows representative electric energy rates as of 1 December 2016. Electricity prices were for domestic (residential), marginal (last consumption band), all usage (not time of use) including GST. Time of Use tariffs could be more or less depending on whether the period was peak, shoulder or off-peak.

In summary, the Energy Rating of a home is a rough guide, giving only the likely electricity cost for space heating and cooling. The Energy Rating helps ensure buildings built in each climate achieve similar indoor comfort levels.

With the regulatory level for NatHERS set at 6 Stars, think of this as being “OK” (it meets the required minimum performance). Think of 7 Stars as “Good”, 8 Stars as “Great”, 9 Stars as “Exceptional”, and 10 Stars as “Amazing”!

As the regulatory stringency may increase over time, there will be a higher need for skilled, professional energy consultants to advise clients on how to improve their building’s performance. Anderson Energy Efficiency is here to do that with you.

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