NCC 2022 Webinar Series: housing energy efficiency

Mark: Hello, and welcome to this presentation on our NCC 2022 housing energy efficiency provisions. I'm Mark Davis your host.

Before we begin, I would like to acknowledge the Traditional Custodians of the land on which we are each participating in this presentation. In my case, this is the Ngunnawal and Ngambri people of the Canberra region. I would like to pay my respects to elders and extend this to all Aboriginal and Torres Strait Islander peoples here today.

Today's presenter is Audrey Chen. Audrey is one of the energy efficiency team members here at the Australian Building Codes Board. Her work involves project managing some of the energy efficiency changes included in the Code. Before we hand over to Audrey, I'd like to cover off the learning outcomes for this presentation. After this session, the aim is that you'll have a better understanding of the NCC and learn the following.

First, be able to describe the changes to the National Construction Code 2022 as they relate to housing energy efficiency. Then, interpret and understand some of these provisions. And lastly, identify when these provisions will be adopted.

Now I'll hand you over to Audrey, who will take you through the content. –

Audrey: To get us started, let's look at what we will cover for houses. Today's presentation will take us through the following:

firstly, the intent of the new energy efficiency requirements and updates; secondly, an overview of key changes to clause numbering. Next, we'll go through the mandatory Performance Requirements for houses, changes to the compliance options and lastly, adoption of NCC 2022 and where you can access further guidance.

Okay, so what is the intent of the new requirements? Let's move on to the next slide. There are 3 objectives, which are to: reduce energy consumption and energy peak demand, reduce greenhouse gas emissions, improve occupant health and amenity, and they also help deliver on the commitment by all Australian governments to reduce greenhouse gas emissions, including the Australian Government's enhanced 43% emissions reduction target for 2030, and commitment to net zero by 2050 which was announced in October 2021.

Okay, let's start with the key changes to clause numbering. One of the key changes is the updates to the clause numbering that occurred throughout the entire NCC. It is referenced to as SPTC, which reflects the new system referencing syntax, Section-Part-Type-Clause. Some examples are shown on the screen [02:56 – 04:00]. Importantly, SPTC retains as much of the previous NCC's referencing system as possible.

To assist practitioners' transition to the new referencing system, NCC 2022 includes NCC 2019 numbering alongside the new numbering. In addition to this, it is also shown on the screen in the table that DTS elemental provisions in section three of NCC 2019.

I will now get into the specifics of the changes, starting with the mandatory Performance Requirements for houses. There are two mandatory requirements that determine the compliance level of energy efficiency for houses: H6P1 covering thermal performance and H6P2 for energy usage.

The main changes to these two Performance Requirements compared with NCC 2019 are the quantification of the Performance Requirements: in NCC 2019, the Performance Requirements are qualitative and subjective in nature. The 2022 quantification changes provide more clarity in how the Performance Requirements should be interpreted by providing measurable indicators to determine compliance. At this stage, for H6P2 only H6P2(1) has been quantified.

Within these new requirements are some additional sub-clauses to reflect the increased stringency and new whole-of-home provisions. I will talk more detailed changes to the Performance Requirements in the next slide.

For thermal performance, the updated Performance Requirement H6P1 models the stringency level at 7 stars equivalent and simplifies the requirement into 3 parts: total heating load, total cooling load and total thermal energy load. The thermal energy load is the sum of the heating and cooling loads. The total heating load, cooling load and thermal energy load can't be more than the load limits calculated in accordance with Specification 44.

Compliance with H6P1 can be met without completing the calculations in Specification 44 if other compliance options are used. For energy usage, there are two clauses under H6P2. The first clause, H6P2(1) shown on this slide, is a newly introduced requirement for whole-of-home energy usage. The energy value of a Class one building's domestic services can't exceed 70% of the value calculated with benchmark equipment. That is: a 3star duct heat pump for heating and cooling, 5-star instantaneous gas water heater and lighting power density of 4 watts per square metre.Please note, both energy values and domestic services are defined terms under NCC.

The second clause, H6P2(2) is the same as an existing clause P2.6.2(a) in NCC 2019. One question you probably have is that how does H6P2(2) relate to H6P2(1)? H6P2(2) focuses on an individual component of system of domestic services. Whereas H6P2(1) sets the minimum overall performance level of regulated key fixed appliances as shown on the previous slide. Both H6P2(1) and (2) need to be satisfied.

I have just covered the mandatory Performance Requirements. Now, I will cover the compliance options to meet these requirements. The compliance level for thermal performance and energy usage is the two Performance Requirements we just talked about, H6P1 and H6P2. For compliance options, we have the Deemed-to-Satisfy, DTS, options in the blue boxes on the left side: Option one, energy rating; and option two, elemental provisions. We also have Performance Solution options in the purple boxes on the right side including Verification Methods. I will cover the DTS options, Verification Methods and Performance Solutions in the rest of the slides.

The most commonly used compliance option is DTS. As shown in the figure on the last slide, for housing energy efficiency, there are two compliance pathways under DTS: use of house energy rating software, which means the Nationwide House Energy Rating Scheme, NatHERS, and DTS elemental provisions.

There is a separate session on NatHERS software. For the NatHERS compliance option, I won't cover the changes to NatHERS software tools. But I would like to highlight a few points for the NatHERS compliance pathway in NCC 2022 for houses.

Firstly, we've consolidated all relevant clauses for the NatHERS compliance option into Specification 42. The star ratings required in Specification 42, clause S42C2 for heating and cooling loads, have been changed to reflect the stringency increase for NCC 2022. The split heating and cooling load limits have been updated, which is included in the next slide, Slide 20. S42C3 Net equivalent energy usage is required if you will use house energy rating software, i.e. NatHERS software, to meet the newly introduced whole-of-home requirements.

I'll discuss this shortly in the Compliance options for the 2nd Performance Requirement Energy Usage. Under S42C4, there are other DTS elemental provisions that need to be met besides NatHERS star rating and heating/cooling load limits. These include requirements for how thermal insulation is installed and the need for a thermal break in some instances.

The new heating and cooling load limits can be accessed from the ABCB website. Another point to highlight for the NatHERS option is that there is a new clause, A5G9 that requires a NatHERS certificate as evidence if using the NatHERS compliance option.

Now I will focus on the DTS elemental provisions for thermal performance. Linking back to the point earlier about NCC restructure, NatHERS compliance option is included in Specification 42 in Volume Two. However, DTS elemental requirements are in Part 13 of the ABCB Housing Provision Standard.

Part 13 of the Housing Provisions includes Part 13.2 Building fabric to Part 13.5 Ceiling fans that are required for thermal performance. Part 13.4 building sealing is the only part totally unchanged from NCC 2019, except numbering differences. Within these provisions, there are new insulation requirements and some increased stringency to achieve 7-star performance Let's start from 13.2 building fabric.

For building fabric, the new elemental provisions identify a broad range of building element properties and R-Values which are deemed to produce acceptable performance. This is done through look-up tables like the one on the screen here [13:49 – 15:10]. On this slide, I've include an example for a pitched roof with horizontal ceiling in NCC climate zone 7.

The applicable R-Value is based on the following factors. First factor is Roof ventilation: Vented or Standard. The table notes explain what is considered as 'Vented'. Otherwise, it is considered as a 'Standard' roof. Then you work out whether there is a reflective insulation under the roof, yes or no. And then, if yes, the under-roof insulation R-Value. For example, vented roof with reflective insulation and under-roof insulation R-value less than one. The last step is to determine the solar absorptance value by finding the corresponding column and you will get the minimum R-value required. So, if the solar absorptance value is between .32 and .42, the minimum R-Value for roof is 4.5.

Clauses 13.2.5 external walls and 13.2.6 floors and subfloor walls of the ABCB Housing Provisions follow the same logic and format as the roof and ceiling. There are a series of look-up tables for different NCC climate zones which are the result of thousands of modelling runs to achieve 7-star thermal performances. Besides solar absorptance value as one of the key factors for wall tables, the size of overhanging and wall height are also key inputs to determine the minimum required level of R-Value for walls. For floor insulation, subfloor walls are part of the consideration in some cases.

When we talk about minimum R-Values for roof, wall and floor in the previous slides, if a dwelling uses metal frame, for NCC 2022, there are additional thermal bridging mitigation measures that need to be met. New thermal bridging requirements align performance of steel-frames to the same level as timber-frames: to meet thermal bridging mitigation requirements for roofs, walls, and floors, there are two ways: firstly, to achieve total R-Values given; and secondly, follow specific mitigation measures outlined in the NCC.

Before we move to the next part on glazing, I just would like to mention that roof light provisions have been changed in NCC 2022 to align with roof light provisions in NCC Volume One.

Now onto glazing. To be better aligned with 7-star NatHERS, there are a set of new glazing factors: level factor, bedroom factor, frame factor, floor factor, and the window openability. Winter and summer exposure factors are also updated to be better in line with 7-star NatHERS. Please note a beta version of the new NCC 2022 glazing calculator and tips in the new NCC 2022 handbook is available on our website.

Ceiling fans facilitate significant reductions in the use of artificial cooling. The ceiling fan requirements have replaced the NCC 2019 requirements for air movement. In Climate zones 1, 2 and3, these requirements include both daytime and nighttime occupied spaces. In Climate zone 5, which is Queensland and New South Wales, ceiling fans are only required in daytime occupied spaces. Ceiling fans are not required in circulation spaces like hallways and entrance foyers. As shown in this slide [19:01 – 19:10], in climate zone 1, 2, and 3, a bedroom with an area less than 15 square metres requires a 900 millimetres ceiling fan.

Next, I'm going to talk through the relevant Verification Methods. These may be used as part of developing a Performance Solution to demonstrate compliance with Performance Requirements. For the housing energy efficiency Verification Methods, both the reference building verification method and the building envelope sealing verification method have been changed.

The Verification Method using a reference building, or VURB, has been changed to reflect the stringency increase. Operating schedules for heating and cooling, thermostat settings, and maximum occupancy are included to provide more clarity for modelling. The Class 1 verification using reference building Verification method only covers the thermal performance requirements, not whole-of-home. This is different to Class 2 apartments. Under the update building envelope sealing Verification Method, if a house is sealed too tight, that is, less than 5 cubic metres per hour square metre at 50 pa, there are additional requirements that need to be met.Although the new updates are in the energy efficiency part, the changes to H6V3, building envelope sealing Verification Method, were included to mitigate condensation risks.

NCC Verification Methods are an agreed assessment method to demonstrate compliance with the Performance Requirements. However, other Performance Solutions may be developed. We touched on earlier in the presentation where I outlined you could use Specification 44 to directly meet thermal Performance Requirement, H6P1, as an option for a Performance Solution.

That wraps up on the compliance options for thermal performance. Next, I'll go through compliance options for the second Performance Requirement Energy usage H6P2.

To meet the new whole-of-home requirements, there are two options under DTS: Using NatHERS whole-of-home software or for a house with a floor area not greater than 500 square metres, using Part 13.6 whole-of-home energy usage in the housing provisions to calculate the net equivalent energy usage. For NatHERS Whole-of-home software, it is required to achieve a score of not less than 60 as shown on this slide [22:00 – 22:30].

I am going to talk you through using Part 13.6 whole-of-home energy usage to calculate the net equivalent energy usage for compliance with H6P2(1). There are 3 steps to meet the whole-of-home requirement outlined in Part 13.6.

Step one, calculate the net equivalent energy usage in accordance with the formula in a. Capitalised A is the floor area factor. EE is the Efficiency Factor covering space conditioning and water heaters. To get the efficiency factors for main space conditioning and main water heater, you need to check the ABCB Standard for Whole-of-Home Efficiency Factors. This standard can be accessed through ABCB's website, which is shown on the next slide. EP and ES are the energy usage calculated for swimming pool and spa pumps. ER is the installed capacity of on-site photovoltaics, PV.

Step 2, calculate energy usage allowance in accordance with b. EF is the energy factor which can be obtained from Table 13.6.2b.

Step 3, compare the results from Step one and 2. If Step one result is less than Step 2, you meet the whole-of-home requirement. You also can use the whole-of-home calculator available on our website instead of manually looking up the whole-of-home efficiency factors and calculating net equivalent energy usage.

Before I give an example for the whole-of-home calculator, I would like to show you the whole-of-home efficiency factor standard. It can be accessed from the ABCB website

 Here is an example using the whole-of-home calculator {24:55 – 25:38]. The heating and cooling uses a heat pump. And the water heater uses an off-peak heat pump. This together with a 7 kilowatt PV to offset, has kept the net equivalent energy usage below the allowance 5.8 kilowatt of PV capacity. Please note that installed PV or ER is not mandatory. You could meet the whole-of-home requirement without PV if the net equivalent energy usage calculated in accordance with a is not greater than the energy usage allowance b as shown in the previous slide.

As mentioned previously, H6P2(2) is an existing provision from NCC 2019. Hence, Part 13.7 Services in the housing provisions must be met for DTS compliance options for both NatHERS compliance option and the compliance with the DTS elemental provisions. Part 13.7 Services is the same as Part 3.12.5 in NCC 2019 Volume Two, except a minimum R-value introduced in NCC 2022 for a swimming pool cover. This change was made based on public comment draft feedback to align with Volume One.

Last but not least, if you want to know more about what I have covered in this presentation, there are few places you can visit. The ABCB resource library has lots of content to help you understand the NCC. You can find the resource library on ABCB website. Our resources include in depth handbooks, helpful articles, and calculators to provide further guidance when working with the NCC, such as the new Housing energy efficiency Handbook. Alternatively, our YouTube channel has many helpful videos to watch at your own pace.

Mark: Thank you for that Audrey. That brings our presentation on the changes to housing energy efficiency in NCC 2022 to a close.

If you want more information, visit abcb.gov.au. Thank you for watching.