In this Net Zero Live session, we tackled energy efficiency, the link to Part O on overheating, as well as cost implications and energy shortages from specifying to meet the new regulations
Last week, I had the pleasure of charing a discussion with industry experts on Specifying for Part L, as part of NetZero Live 2022.
With updates to Approved Document L, or Part L, of the Building Regulations for England coming into force on 15 June 2022, meeting the new regulations has been a pressing concern for those within the industry.
The updated regulations aim to lower the operational carbon emissions of new homes, raise fabric efficiency standards and introduce a new level of quality control. But what effect will this have on the products that we specify?
The panellists outlined the fabric requirements, explained the specification responsibilities from a Part L perspective and importantly, how decisions can impact compliance.
We tackled energy efficiency, the link to Part O on overheating, as well as cost implications and energy shortages, with the panel presenting case studies to demonstrate practical solutions that meet the new requirements.
David Adams, strategic advisor at Future Homes Hub, kicked off the session by taking us through some of the emerging themes. The Future Homes Hub is supporting the wider housebuilding industry’s transition towards and beyond the Future Homes Standard 2025.
Adams highlighted the arrival of FLOS (Part F, Part L, Part O and Part S) and the importance of considering your projects in the context of all four documents. There is a 12 month transition period for the new regulations but if your building notice was prior to June 2022 then you need to have started on site before June 2023, otherwise the new regulations will apply.
The updated regulations aim to lower the operational carbon emissions of new homes, raise fabric efficiency standards and introduce a new level of quality control
Adams noted that Part O on overheating should be tackled prior to Part L as it will “impact lots of different aspect in the design of the dwellings”. As a new regulation, it is one the industry are unfamiliar with but necessary to help homes now and in the future from overheating.
Cill heights have increased, solar gain needs to be reduced (smaller windows, certainly on some facades or incorporating shading) and more active measures will also be needed to reduce excess heat through air conditioning as a fallback option.
“Another big change is the emphasis on construction details”, added Adams. In the past, we have been able to use a fairly generic approach but under the new regulations, that will no longer stand. Every thermal bridge will need to be specified and built on site to those drawings. There is now an element of photographing what you have built before it is covered as part of the compliance process.
There is also a follow on QA process that demonstrates those assumptions that have been put into the energy model have been undertaken on site. “This is a significant shift in practice,” highlighted Adams.
Other changes include the reduction of flow temperatures to radiators, thicker walls and floors, enhanced ventilation strategies and specifications of key elements being recorded and provided to the home owner.
Future Homes Hub have produced some help and guidance, not a “how to” but a “where to start”, which can be accessed here.
Cill heights have increased, solar gain needs to be reduced (smaller windows, certainly on some facades or incorporating shading) and more active measures will also be needed to reduce excess heat through air conditioning as a fallback option.
Lidia Guerra, senior engineer at Max Fordham shared details from a building services and energy perspective, covering early lessons she learned through modelling.
Guerra raised an important point on the carbon emissions aspect. While the gas carbon factor remains unchanged, the electricity carbon factor is steadily declining. Currently at 0.136 kg/kWh, for the first time the electricity carbon factor is lower than gas. Meaning “if you’re using electrical systems in your building, you’re likely to have an advantage”.
There are now three parameters in Volume 1 of Part L. There were previously two. The new metric relates to the dwelling primary energy rate (DPER) and must be no higher than Target (TPER) - kWh/m2 per year. This is influenced by your fuel. “Photovoltaics and Waste Water Heat Recovery (WWHR) are now included in the notional,” added Guerra.
Guerra shared some lessons learned from modelling projects to meet the new requirements. From heat pumps proving to be quite straightforward in terms of meeting the new parameters to WWHR being significant in terms of absolute numbers, particularly when relating to projects such as care homes, where there is a high water load.
“There are a number of fabric changes with quite demanding u-Values,” added Guerra.
The London Plan remains unchanged, with an onsite carbon reduction of at least 35% beyond Part L needing to be achieved. Teams are asked to investigate connecting to an existing or planned district heating network as well as explore renewables and maximise PVs on roofs. Guerra went on to say “because the notional is getting better, it’s becoming harder to achieve this.”
The London Plan remains unchanged, with an onsite carbon reduction of at least 35% beyond Part L needing to be achieved.
Claire Young, senior engineer at Civic Engineers highlighted the importance of being fully coordinated across the design team, particularly advocating for early coordination between MEPs and structural engineers to create an integrated design.
Structural engineers have slightly less impact on operational energy, which is what Part L is concerned with. But they do have an impact by working with architects on fabric design, looking at air tightness and thermal bridging.
Young advised against using too many different materials: “The more you bring in, the more detailed your design is going to be and the more thermal bridging is required.” She went on to highlight the importance of allowing for the lifespan that your building is intended by “making sure the materials and products that you’re using are either spec’d for that lifespan or can be easily replaced.”
Young reminded us of the huge role construction plays in the fight against climate change. 10% of the UK’s carbon dioxide emissions are directly associated with construction, which includes the CO2 generated through the entire building process. Embodied carbon will be responsible for almost half of total new construction emissions between now and 2050. “I find that quite an empowering statement,” said Young, as she feels it’s something the industry can tackle.
Civic Engineers advocate making carbon a core pillar, equally as important as quality, cost and time. By embedding carbon - both embodied and operational, all the way to whole-life carbon - as a constraint, it will become a primary factor that people can no longer opt in and out of.
We ended the session with a Q+A, discussing product passports, carbon calculations and whether the panel believe the new requirements are particularly ambitious.
As well as exploring hydrogen as a fuel for heating homes, all-electric heating and the grid’s capacity for our shift toward more sustainable energy sources.
Our session, alongside all of the Net Zero Live sessions are available free on-demand for 12 months. You can access them here.
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