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Wed February 24 2021

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Future Homes Standard sets new targets for green building

20 Jan The Ministry of Housing has set out new energy efficiency standards that all new-build houses will be expected to meet.

Responding finally to the 2019 consultation on its Future Homes Standard, the government has decided that all new homes will have to have low carbon heating and be ‘zero carbon ready’ by 2025.

This means that no further retrofit work will be necessary to enable them to become zero carbon homes as the electricity grid continues to decarbonise.

New homes are expected to produce 75-80% lower carbon emissions compared to current levels by 2025.

In 2019 the government introduced a legally binding target to reduce greenhouse gas emissions to net zero by 2050. Making houses less energy intensive is all part of this.

While there is nothing about upgrading the existing housing stock, the standard does set down energy requirements for extensions or building improvement/renovation works.

Housing minister Christopher Pincher said: “Improving the energy performance of buildings is vital to achieving net-zero emissions by 2050 and protecting the environment for future generations to come.

“The radical new standards announced today will not only improve energy efficiency of existing homes and other buildings, but will also ensure our new homes are fit for the future, by reducing emissions from new homes by at least 75%.

“This will help deliver greener homes and buildings, as well as reducing energy bills for hard-working families and businesses.”

The government plans include measures to tackle ventilation: a new requirement for additional ventilation and indoor air quality monitoring in high-risk non-domestic buildings such as offices and gyms, reducing the risk of infections being spread indoors.

There will also be a new overheating mitigation requirement in the building regulations.

Transitional arrangements will last for one year and apply to individual homes, rather than an entire development.

The government has also announced a consultation on higher performance targets for non-domestic buildings to make them ‘zero carbon ready’ by 2025.

The government’s consultation was the first part of a two-part consultation on Part L and Part F of the building regulations.(For the results see: The Future Homes Standard: summary of responses, and government response.)

Plans to make all other buildings, including existing homes, more energy efficient have been published today as part of the Future Buildings Standard consultation.

This is the second of the two-part consultation on Part L and Part F and proposes new energy and ventilation standards for new and existing non-domestic buildings and existing domestic buildings, as well as addressing overheating in residential buildings.

Industry reaction

Julie Hirigoyen, chief executive of the UK Green Building Council, said: “After a long wait, the government’s response to the Future Homes Standard consultation brings much-needed clarity to our industry. We are pleased to see confirmation that the Future Homes Standard will mean new homes will have carbon dioxide emissions 75-80% lower than those built to current Building Regulations – though it’s regrettable that the Standard won’t be implemented till 2025, despite it being widely trailed that it would be brought forward to 2023. We also welcome the interim 31% threshold later this year, which will put us on a path to the Future Homes Standard.

“It’s a big relief that the government has ditched its original proposal to scrap the Fabric Energy Efficiency Standard (FEES). We had long argued that scrapping the FEES would be a highly retrograde step, meaning in some cases that a home that would fail current Building Regulations because of poor fabric could pass the 2021 regulations. Meanwhile, the many local authorities that have declared climate emergencies will also be relieved that government has confirmed that in the immediate term they can still set higher energy performance standards for new homes than those mandated by building regulations. But they, like us, will be disappointed that government hasn’t completely ruled out curtailing their powers in the future.”

Alan Fogarty, a partner at consulting engineer Cundall, said the new standard failed to address the retrofit challenge. “The Covid-19 pandemic has pushed the sustainability agenda further into the spotlight, and with demand for net zero carbon buildings increasing by the day, these rigorous new standards are very welcome,” he said. “Furthermore, the focus on the levels of overheating in domestic is an important development. However, while this is great news for the energy performance of new build homes and businesses, the fact remains that 90% of building stock that will be in use in 2050, has already been built to standards that do not comply with net zero carbon standards. The real challenge here is retrofitting the thousands of homes and businesses in our existing building stock. In order to meet the government’s ambitious 2050 net zero carbon targets, we need to be retrofitting 20,000 homes per week to meet net zero carbon energy standards, and at the moment there is no standard in place for how that should be achieved.”

The Federation of Master Builders expressed similar concerns. Chief executive Brian Berry said: “A focus on future homes shouldn’t forget Britain’s 28 million existing homes, many of which are energy inefficient, and 85% of which will still be in use in 2050. These homes need to be retrofitted to help deliver the government’s net zero carbon targets as well as creating much-needed jobs and training opportunities in each community across the country.”

Draft Future Homes Standard specification

 
Floor U-value (W/m2.K) 0.11
External wall U-value (W/m2.K) 0.15
Roof U-value (W/m2.K) 0.11
Window U-value (W/m2.K) 0.8
Door U-value (W/m2.K) 1.0
Air permeability (m3/(h.m2) 5.0
Heating appliance Low-carbon heating (e.g. Heat pump)
Heat Emitter type Low temperature heating
Ventilation System type Natural (with extract fans)
PV None
Wastewater heat recovery No
y value (W/m2.K) 0.05

Notional building specification for Part L 2021

Element or System   Reference Value for Target Setting  
climate data   • UK average  
       
size and shape   • Same as actual dwelling  
       
opening areas (windows, roof windows, rooflights and doors)   • Same as actual dwelling up to a maximum for total area of openings of 25% of total floor area.1  
       
external walls including semi-exposed walls   • U = 0.18 W/m²K  
       
party walls   • U = 0  
       
floors   • U = 0.13 W/m²K  
       
roofs   • U = 0.11 W/m²K  
       
opaque door (<30% glazed area)   • U = 1.0 W/m²K  
       
semi-glazed door (30-60% glazed area)   • U = 1.0 W/m²K  
       
windows and glazed doors with >60% glazed area   • U = 1.2 W/m²K  
    • Frame factor = 0.7  
    • Solar energy transmittance = 0.63  
    • Light transmittance = 0.80  
    • Orientation same as actual dwelling  
    • Overshading same as for compliance calculation (average if actual dwelling has very little or average overshading; same as actual dwelling if greater overshading)  
       
roof windows   • U = 1.2 W/m²K (adjustment factor of +0.3 W/m²K applied to roof window as described below Table 6e; resultant U value = 1.5 W/m²K).  
    • Overshading factor 1.0. Other parameters as for windows.  
       
rooflights   • U = 1.2 (no correction applied) Overshading factor 1.0. Other parameters as for windows  
       
curtain wall   • Curtain walling to be treated as standard glazing and opaque wall with the same areas as the actual dwelling.2  
       
thermal mass   • Same as actual dwelling  
       
living area   • Same as actual dwelling  
       
number of sheltered sides   • Same as actual dwelling  
       
allowance for thermal bridging   • Thermal bridging allowance is calculated using the lengths of junctions in the actual dwelling and the ‘Option 2’ psi values in Table R2.(www.bregroup.com/sap/sap10/)  
       
ventilation system   • Natural ventilation with intermittent extract fans  
       
air permeability   • 5 m³/h·m² at 50 Pa  
       
chimneys and open flues   • None of any type.  
       
extract fans/ passive vents   • 2 extract fans for total floor area up to 70 m², 3 for total floor area > 70m² and up to 100 m², 4 for total floor area > 100 m²  
       
main heating fuel (space and water)   • Mains gas  
       
heating system • Boiler and radiators    
  • Central heating pump 2013 or later, in heated space    
  • Design flow temperature = 55°C    
       
boiler • If gas or oil combi boiler performing space heating in actual dwelling, instantaneous combi boiler; otherwise regular boiler.    
  • Efficiency, SEDBUK (2009) = 89.5%    
  • Room-sealed, fan-assisted flue; modulating burner control, no hot water test for combi boiler    
       
heating system controls • For a single storey dwelling in which the living area is greater than 70% of total floor area, programmer and room thermostat    
  • For any other dwelling, time and temperature zone control, TRVs    
  • And in all cases:    
  • Boiler interlock    
  • ErP Class V    
       
hot water system • Heated by boiler (regular or combi as above).    
  • Separate time control for space and water heating    
       
showers and baths • Number of showers and baths same as actual dwelling. If shower(s) specified, shower flow rate(s) to be 8 l/min.    
  • Shower(s) supplied by main water heating system (not instantaneous electric shower).    
       
wastewater heat recovery • All showers connected to WWHR including showers over baths    
  • Instantaneous WWHR with 36% recovery efficiency utilisation of 0.98, wastewater fraction 0.9.    
       
hot water cylinder • If cylinder specified in actual dwelling: volume of cylinder in actual dwelling    
  • If combi boiler: no cylinder    
  • Otherwise: 150 litres If cylinder, declared loss factor = 0.85 x (0.2 + 0.051 V2/3) kWh/day, where V is the volume of the cylinder in litres    
       
Primary water heating losses • Fully insulated primary pipework.    
  • Cylinder temperature controlled by thermostat cylinder in heated space    
       
water use • Limited to 125 litres per person per day    
       
secondary space heating • None    
       
lighting • Fixed lighting capacity (lm) = 185 x TFA Efficacy of all fixed lighting = 80 lm/W    
       
air conditioning • None    
       
PV system • For houses kWp = 40% of dwelling floor area / 6.5    
  • For flats kWp = 40% of dwelling floor area / (6.5 * number of storeys in block)    
  • System facing SE/SW    
  • Overshading is ‘none’    
  • Connected to dwelling’s meter for houses    
  • Not connected to the dwellings meter for flats    
       
 

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