New Scottish Building Regulations Torpedo a Solar Success Story

On December 22nd 2023 Scottish Government published an update to the Building Standards Technical Handbook which will apply to new building sites where a building warrant is applied for after April 1st 2024.

The update to the handbook was made to implement the New Build Heat Standard which bans the use of ‘Direct Emission Heating Systems’ - gas or oil boilers in plain English - from newly built homes and some conversions of existing properties.  Instead, developers must now choose from a heat pump, direct electric heating (storage heaters or infrared panels) and connecting to a heat network (if available).

In 2015 Scottish Government introduced solar PV into its building regulations - well ahead of England which was to take until 2021 to catch up.  This has resulted in a thriving solar industry in Scotland, installing far more solar to domestic properties per head of population than the rest of the UK (see my earlier blog: How Progressive Building Regulations Made Scotland a Solar Powerhouse).  

Unfortunately, Scottish Government has ignored repeated warnings from Solar Energy Scotland that the introduction of the New Build Heat Standard without an accompanying adjustment to the Building Standards could threaten the success story of Scottish solar.

Working in Silos

To understand how the new regulations could harm the solar industry in Scotland we need a little background on how the building regulations work.  The regulations are not prescriptive, they aim to give the designer freedom to choose how to build the house - instead of defining each and every building element, the set a level of  energy performance that the house must achieve.

A developer must show that the house they are planning to build uses no more energy than a home of the same size and shape built according to a defined specification called the Notional House Specification.  (For more details on how this works see my earlier post on Energy in Building Regulations).  Over time the regulations have made new homes more and more energy efficient by changing the Notional House Specification to have a better and better energy performance.

The last major review of Building Regulations in Scotland (in 2021) introduced two specifications for the notional house - one for homes with heating by a gas boiler, the second for a house with a heat pump.

In order to 'nudge' developers towards using more heat pumps and away from polluting gas boilers the specification with the heat pump included a number of cost-saving relaxations in other areas - notably the omission of solar PV panels which were included in the gas heating specification. 

Although it might have been an admirable intention to nudge developers towards heat pumps (it didn't work by the way - gas boiler and solar remained the preferred design choice), it was clear that if the New Build Heat Standard was to come in without changing the notional house specification at the same time, then the only legal specification becomes the one with the heat pump, and solar would be dropped from the notional house in Scotland for the first time since 2015.

Unfortunately we were talking to two different sets of officials from Scottish Government - one working on the building regulations and the other working on the New Build Heat Standard.  Our concerns were ignored.  The latest regulations have enacted the boiler ban and left the Notional House Specification unchanged.

The Impact on Solar  for New Homes in Scotland

This unwelcome development is not necessarily all bad news for solar.  

First of all, housebuilders may choose to combine solar PV with a heat pump in their designs, not least as a way of keeping a lid on energy bills for their customers.  This change to the building regulations is probably the first ever update to result in higher bills for consumers.  Electricity costs far more than gas does - and the enhanced efficiency of heat pumps does not make up for the difference.  Developers can offset this rise in bills by keeping solar in their design.

Secondly, solar has become a common sight in new developments across Scotland and customers have come to expect it on new homes and increasingly see energy efficiency as a reason to buy new rather than in the general housing market.

Third the gas boiler plus PV specification still applies to homes with direct electric heating.  Developers may explore this option, adding better insulation to the point where space heating demand is reduced to an absolute minimum - especially for smaller properties.

Finally, since new regulations only come into force from the point of applying for a building warrant it is likely to take a year or so before sites begin construction under the new regulations, and 2-3 years before the majority new homes being built are to the new standard.  What could change in this time?  Here are some thoughts:

• Alex Rowley MSP proposed that Scotland move to a Passivhaus basis for building regulations, and in December 2022 Scottish Government announced that it would legislate for this by December 2024.  We may have a new version of the regulations in less than 12 months time.
• The European Commission announced a strengthened Energy Performance of Buildings Directive in December 2023 in which "Installing solar energy installations will become the norm for new buildings".  The current Scottish Government is very keen on aligning its regulations with the EU with its goal of quitting one union and re-joining another.
• A new Future Homes Standard for England is embracing smart energy, time of use electricity tariffs, energy storage and solar generation with a new half-hourly calculation method, and is beginning to make the Scottish approach look rather passé.  A strong Future Homes standard specification with heat pump and solar will encourage the Scottish Government to surpass it.
• Who knows how far battery storage, solar and smart energy technology will developed by this time?  If we were to go back four years, battery storage was only for dedicated enthusiasts and off-grid applications - now it's included with around half of all retrofit solar installations.  The performance and cost of solar and energy storage continues to make the technology more widely applicable and attractive.  More recent innovations such as time of use tariffs and electric vehicle to grid charging will only add to the advantages of having solar on your home.

Whether the omission of solar PV from the notional house specification in Scottish building regulations slows the adoption of solar PV in Scotland remains to be seen.  What is clear is that, at worst, it will only temporarily slow its rise.

 

Scotland to Adopt Passivhaus Standard for new Houses

 

Linn Way, Garelochhead - a Passivhaus Development of 10 homes by Argyll Community Housing Association (ACHA) 

On 15th December 2022, Patrick Harvie, Minister for Zero Carbon Buildings, Active Travel and Tenant's Rights (there's a job title for you), wrote to Alex Rowley, a member of the Scottish Parliament to inform him that his campaign for new homes in Scotland to be built to Passivhaus standard would become law.

Back in November, Rowley had  introduced a Member's bill to the Scottish Parliament, the "Proposed Domestic Building Environmental Standards (Scotland) Bill" – which would introduce new minimum environmental design standards for all new-build housing to meet a Scottish equivalent to the Passivhaus standard.

The bill followed on from a public consultation which Rowley had organised earlier in the year.  

The consultation received 629 responses which included submissions from  Cala Group Ltd,  Barratt Developments PLC, the Scottish Federation of Housing Associations and The Royal Incorporation of Architects in Scotland - people were taking this seriously!

Having garnered the support of more than 18 MSPs from at least two political parties, the Bill was due to be debated in the Scottish Parliament.  Instead the Scottish Government choose to avoid the debate by announcing that it intended to give the Bill effect through subordinate legislation within two years.

"I hereby state that the Scottish Government will make subordinate legislation within two years, to introduce new minimum environmental design standards for all new-build housing to meet a Scottish equivalent to the Passivhaus standard"  Patrick Harvie MSP, 15 December 2022

So where does this leave the future direction of Scottish Building Regulations?

The Passivhaus standard is remarkably simple to summarise

1. Maximum space heating demand cannot exceed 15kWh per square metre of net living space per year, or 10W/m2 of peak demand

2. The Primary Energy Demand (total energy used for all domestic applications (heating, hot water and domestic electricity) must be less than 60kWh/m2 per year.

3. Airtightness cannot exceed 0.6 air changes per hour at 50 Pascals pressure.

A key difference between the Passivhaus standard and the Scottish (and rest of UK) building regulations is that Passivhaus is absolute while Building Regulations are relative.  

UK building regulations work by taking a house shape you want to build, calculating the annual energy use if that house was built following an approved specification (the notional house).  The specification for the house you build cannot be worse than the notional house.  

You can read more about how UK building regulations for energy work in this earlier post.

Buildings that minimise the ratio of their surface area to their inside volume are intrinsically more energy efficient than buildings with a high surface area to volume ratio.  Simple rectangles outperform complicated (but architecturally appealing) building forms with cross wings, porches, bay windows, dormer windows and the like.  Large buildings out perform smaller buildings on this measure too.  Linked buildings (terraced, semi-detached) outperform individual buildings.

Credit: BRE Passivhaus Designers Guide

Passivhaus rewards efficient building form because it is concerned with the absolute energy use, UK building regulations ignores building form because it compares the performance of that house design with a notional house of the same shape.

In terms of the resulting specification that might achieve the standard, the Passivhaus Institute estimates that for most cool-temperate climates : 

Walls, floors, roofs: A heat transfer coefficient (U-value) of 0.15 W/(m²K)

Windows:  U-value of 0.80 W/(m²K) 

The notional house specification for Scottish Building Regulations 2022 uses a U value of 0.15 for walls, 0.12 for floor, 0.09 for roofs and 1.2 for windows.   So with the exception of windows, Scotland will be building homes that already largely meet or exceed the specification, so long as building shape and orientation does not require higher levels.

Air permeability is 5m3/h.m2 in Scottish Building regulations notional house.  Taking a storey height of 3m, this translates into 1.67 air changes/hour.  To get to 0.6 air changes/hour will require a big improvement to an area that has proven to be challenging in the past, especially when building in volume with traditional methods rather than off-site manufacture.

The final big change is  that Scottish (and UK) Building Regulations only consider energy used for space heating, domestic hot water, and electricity for lights and services (pumps and controls).  It ignores the main part of electricity used in the house to run appliances and plug-in devices - a weakness that becomes increasingly noticeable as homes become better insulated.

By contrast the Primary Energy Demand requirement in the Passivhaus standard considers all the energy use in the property with allowances for electricity consumption by residents using appliances and electronic devices.

It is worth noting that energy generated by Photovoltaic (PV) systems may not be counted against the Primary Energy target in the Passivhaus calculator (called PHPP). This is a deliberate implemented to prevent poor standards of energy efficiency being offset by the use of renewable energy.  As emerging technology maximises the use of solar generated electricity (for example solar diverters and battery storage), this is looking increasingly anachronistic.

The Passivhaus Institut is moving towards including PV  generation in Passivhaus certification. This will be in the form of new classes "Passivhaus Plus" and "Passivhaus Premium". These standards require the same fabric standard as any other Passivhaus but higher reductions in the primary energy demand compared with the existing Passivhaus standard, normally achieved using on-site generation.

This decision by the Scottish Government has really has the potential to overturn an orthodoxy that for years has based energy efficiency standards for homes on the government's own calculation - the Standard Assessment Protocol (SAP), which has been the overarching mechanism to demonstrate compliance with building regulations on energy for decades.  

How revolutionary this change turns out to be, well, time will tell - after all the Scottish government only committed to a 'Scottish version of Passivhaus' which could be as limited as a new version of SAP with exceptionally high U values and airtightness in the notional house.  Alternatively if the founding principles of Passivhaus are followed, it could turn out to be a radical shift in the way the building regulations are delivered in the UK.

New Building Regulations for Scotland

In June 2022 the Scottish Government published its consultation response on changes to further tighten the Building Regulations for energy efficiency.  New developments in Scotland seeking a Building Warrant after 1 December 2022, will need to meet the new regulations.

Although most respondents to the consultation were in support of a higher performance target (delivering a 57% reduction in CO2 emissions), the government instead opted for the lower performance target which is expected to reduce the CO2 emissions of new homes in Scotland by 32%.

The central element of the building regulations for energy is the so-called 'Notional House Specification' which defines the target that a developer must meet. (For a full explanation of how the Notional House Specification works see this earlier blog).

The 2022 Building Regulations in Scotland gives three Notional House Specifications - one for homes heated with a heat pump, another for homes heated by a heat network and a third based on mains gas  for homes using any other heating systems.

The table below contrasts key elements of the new Notional House Specification with those in the previous version of Scottish Building Regulations and also with the new regulations that came into force in England this year.

As can be seen, the new Scottish Building regulations require a significant improvement in U-values (insulation) and airtightness compared to the current (2015) regulations.  They also come in slightly better than the latest regulations for England (it would have been a major surprise if they didn't!)

Of interest to solar industry participants will be the increase of PV provision in the gas heated notional house compared to the 2015 regulations.  

In 2015 Scotland became the first of the nations to add solar PV to the notional house - the amount asked for was the dwelling total floor area in m2 x 0.01kWp, which corresponds to 20Wp of solar per 1m2 of ground floor area (for a two storey building of equal ground and first floor areas).  The new requirement is for 0.4 x ground floor area in m2 / 6.5 -  which works out to be 62Wp of solar per 1m2 of ground floor area - around 3 times more solar per house.

Other Changes

Scottish Goverment also changed the way the benefits from solar are taken into account in the calculation.  The energy and carbon benefit of on-site generation is capped at the level assessed as being used on site (excluding the energy exported the grid).  This change is likely to incentivise the use of technologies to store excess solar energy for later use - for example battery storage or energy diverters that heat hot water with excess solar energy.

Good News for Solar?

The new regulations look like great news for solar in Scotland.  The Building Regulations are 'solution neutral' allowing developers to choose a combination of heating system, insulation and on-site generation that equals or exceeds the performance of the Notional House Specification.  Since both developers and house buyers prefer gas boilers to heat pumps, this regulation change is likely to increase the amount of solar installed on new homes in Scotland because of the three-fold increase in panel power in the specification.

However, the cloud on the horizon for the solar industry is another piece of legislation - the New Build Heating Standard, which will remove the gas boiler option for housebuilders by banning their use in new homes.  

Under these Building Regulations, once a housebuilder is forced to use heat pumps, the requirement for solar drops away because the Notional House Specification for heat pump heated homes does not include it.

Solar PV and heat pumps are a great match, with solar offsetting higher running costs of heat pumps - why would Scottish Government have no solar on the heat pump specification?  It all boils down to the cost for the developer - the regulations have been set up to encourage housebuilders to consider heat pumps before the 2024 regulations, and the notional house has been set up to try to level the playing field for build costs - leaving waste water heat recovery and solar off the heat pump specification.

No heed has been paid to the increased running costs the home owner will suffer in a heat pump heated home compared to a home with a gas boiler and solar PV.

Once there is a regulatory requirement in place to use a heat pump, then then the incentive to try to lower the cost of a heat pump installation versus gas plus solar falls away.  Scottish Government should commit to review the building regulations at the same time as bringing in its New Build Heat Standard to require solar PV on heat pump heated homes too.  This way it will ensure a just energy transition and reduce the risk of a consumer rejection of heat pumps.

Comparing Building Regulations for Energy - Scotland and England

 

Development of new homes in Glasgow by CCG Homes, Installation by Arc-Tech

New regulations have been published for Part L building regulations in England.

Let's take a quick look at how they compare to Scotland, where almost all new homes now come with solar panels.

The building regulations work by defining a specification for a 'Notional Dwelling' - read this article for more detail of how it works

In the table below I have shown a selection of the more significant requirements for each.  It is evident that not only do both Notional Houses include solar PV, but that the England requirement is much higher.

Housebuilders do not have to build the Notional House specification, but they must equal or exceed its performance.  The scope for reducing the solar provision by increasing the insulation performance of building elements such as walls, roofs and windows (collectively often referred to as fabric measures)  is limited in the new English regulations, which equal or exceed the fabric requirements in Scotland.

‘Notional Dwelling’ Summary Specification Selected Requirements
	Scotland 2015 (Gas Package)	England 2021
U Values in W/m2K
External Walls	0.17	0.18
Floors	0.15	0.13
Roofs	0.11	0.11
Doors	1.40	1.00
Windows	1.40	1.20
Air Permeability	7 m3/h.m2 at 50Pa	5 m3/h.m2 at 50Pa
Heating	Gas boiler 89% efficiency	Gas boiler 89.5% efficiency
Heat Emitter Type	Regular radiators	Low temperature heating 55°C flow
Heat Recovery	Instantaneous Waste Water 45% efficient	Instantaneous Waste Water 36% efficient
Solar PV in kWp	Smaller of (a) Total floor area (m2) x 0.01   (b) 0.3 x roof area based on 30 degree roof pitch x 0.12	40% of dwelling floor area/6.5
Example solar PV for 85m2 house with two floors	0.85kWp	2.6kWp

The Future Homes Standard Consultation

Where next for Building Regulations?

In the week where Extinction Rebellion activists were arrested for hosing the Treasury in 'blood' in protest at the lack of progress on tackling a climate emergency, the consultation on the Future Homes Standard came out.  There's talk of solar panels for all new homes - so let's take a look under the hood of the consultation.

The consultation itself consists of two main parts - consideration of the Future Homes Standard due to come into force in 2025 which is intended to deliver "world-leading levels of energy efficiency" for new homes and  an update to the Building Regulations Part L (energy efficiency) and Part F (ventilation) in 2020 to provide a "meaningful but achievable" uplift in energy efficiency as a first step towards the 2025 vision.

There's also a raft of supporting documentation

The Standard Assessment Procedure (SAP) calculation version 10.1
An Impact Assessment, which includes details of cost assumptions
Approved Documents L and F 

2020 Part L - a Stepping Stone to Future Homes 2025

There's a lot to talk about here.  This is no 'tweak' but a significant revision, at least in part forced by the significant changes to the carbon intensity of grid electricity, but also by the Grand Challenge Mission for Buildings, announced by Theresa May about a year ago.

1. Primary Energy Use is the new Gold Standard

Until today, Part L has always used carbon dioxide emissions as its measure of compliance with regulations.  Buildings had to achieve a certain Dwelling Emissions Rate (DER) in kgCO2/m2.

DCLG has rightly concluded that as the electricity provided by the grid comes with a lower and lower carbon intensity, developers could switch to electric heating and hit a carbon target without improving the energy efficiency of buildings.  If energy efficiency of buildings is not improved, then decarbonising the grid becomes more challenging and costly.  So a new measure is required and primary energy, which has the benefit of aligning UK regulations with the measures chosen in the EU Energy Performance of Buildings Directive, is added as a new metric.

(See this article on the rapid progress made in decarbonising the grid.)

The latest revision to the government's Standard Assessment Procedure (SAP) version 10.1 has been published alongside the consultation.  This is the calculation used to demonstrate a house complies with the building regulations.  In this version of SAP the carbon intensity of electricity is set to 136gCO2/kWh, a projection of the average from 2020-2025, and a massive reduction from the value of 519gCO2/kWh in the current version of SAP 2012.  Electricity now produces less than 65% of the carbon emissions of mains gas (which is at 210gCO2/kWh).

By contrast, the primary energy content of a unit of electricity is 1.501 compared to gas at 1.130.

This document explains primary energy and how the values were arrived at

Fitting solar PV to a property reduces the grid electricity that is needed by the house, solar PV generation used in the building (self-consumption) reduces both the carbon emissions and primary energy by the same factor as grid electricity.

Electricity sold to grid also reduces both the carbon and primary energy use of the dwelling but it's primary energy factor is only 0.501.

The impact of this is that a unit of electricity generated by PV and used in the building would save 1.501 kWh of primary energy use, but a unit of PV generated electricity exported to the grid would only save 0.501 kWh of primary energy use in the calculation.

Since the benefits of battery storage (SAP Appendix M) and PV diverters (SAP Appendix G4)  have also been added to this update to SAP, the combination of using primary energy as the main regulatory target and the low primary energy factor for PV export has the effect of incentivising measures such as these to use as much PV-generated electricity within the building.

The trouble with this is that

(a) developers prefer combi boilers so there's no hot water cylinder in most new homes for a PV diverter to divert excess electricity into.
(b) batteries are approaching cost effectiveness but are likely to be seen by developers as an additional cost and not a sellable benefit.

We understand that the logic for choosing this value for exported energy is that the exported energy has a primary energy factor of 1.0 (renewable energy), and displaces a unit of energy from being fed into the grid at the grid average of 1.501, so the net benefit to primary energy added to the grid is 0.501.

The solar industry might argue that considering things from the point of view of the building produces a different logic (and after all what we're supposed to be modelling is the energy performance of the building).  The net primary energy consumption of the building is the electricity imported at a primary energy factor of 1.501 less the PV generated electricity exported which should have a primary energy factor of 1.0. 

A minimum carbon emissions requirement is retained in addition to the primary energy requirement as this remains an important consideration for government and there is concern that certain solutions could produce low primary energy figures with high carbon emissions - for example heating oil and coal both have low primary energy but  high associated carbon emissions.

Finally, the current fabric efficiency requirement is dropped to make way for a new householder affordability target, with fabric efficiency now considered adequately protected by tougher minimum heat loss standards for building elements.  As discussed, electricity has low and falling primary energy and carbon emissions factors, and government is concerned that direct electric heating would be a viable option for meeting both the carbon and primary energy targets, but with the side-effect of saddling occupants with too-high energy bills.  To guard against this the new affordability rating is likely to be set at a level that means direct electric heating would only be an option when combined to other measures to reduce electricity bills such as increased thermal insulation, PV panels or battery storage.

2. Uplift of the Minimum Standard

The minimum performance standard is defined by publishing a build specification (insulation levels, heating system, light fittings, microgeneration technologies) to be used by the developer to model a 'notional house'.  The developer then has to design the house they plan to build to produce modelled carbon emissions and primary energy lower than that of the notional house.  It's an elegant way to allow the developer complete freedom in design but control the outcome.

 The consultation proposes two options for the minimum performance standard:

Option 1 - "Future Homes Fabric"

This specification would produce a 20% reduction in CO2 emissions when compared against the specification in current building regulations .  The standard is based on a notional home with improved insulation measures (including triple glazing) plus a gas boiler and waste water heat recovery.

The estimate given in the consultation is that this option adds £2557 to the build cost of a semi-detached house and saves households £59 a year in energy bills.  (Payback 43 years)

Given that by 2025 the Future Homes Standard needs to be at a 75% of the carbon emissions of 2013 regulations, 20% does not seem like a big enough step - it only brings England roughly to the level that  Scotland's developers have been achieving since 2015.  DCLG appears to agree, stating that it's preferred option is Option 2.

Option 2 - "Fabric plus Technology"

In this option, the specification of the notional house is set at a level to produce a 30% reduction in carbon dioxide emissions across the build-mix.  The specification has slightly lower insulation than Option 1 plus waste water heat recovery and a solar PV system.

SAP 10.1 Appendix R outlines the specification for the notional house.  The size of the PV system in kWp for the notional house is 40% of the building foundation area divided by 6.5.  So for example for a typical two-storey semi-detached house of total floor area 85m2, this would be

[40% x (85/2) ] / 6.5 = 2.6kWp (around 9 or 10 panels)

DCLG's modelling estimates that building to this new notional home adds £4847 to the building costs and saves £257 a year in energy bills.  (Payback 19 years).

The costs used in the accompanying impact assessment for solar PV are £1,100 fixed costs plus £800 variable per kWp installed.  This implies the following installed costs:

1kWp  £1,900  £1.90/kWp
2kWp  £2,700  £1.35/kWp
3kWp  £3,500  £1.17/kWp

Solar is a fast-paced technology and it would be unusual if a government consultation were to use up-to-date cost information.  My understanding is that solar installers operating in the new-build sector are typically charging an installed price the range of £1.10-£1.20/kWp for four or five panel systems (1 -1.25 kWp).  So it is likely that the costs of Option 2 are over-stated relative to Option 1.

If the solar industry can provide evidence that costs in Option 2 are over-stated, it will make it easier for government to hold the line on its preferred option.

DCLG reckons that Option 2 might result in developers moving away from gas boilers to air-sourced heat pumps.  A specification based on ASHP alone over-shoots the Option 2 target at a lower cost than the notional house (£3,134), which would allow some relaxation of the fabric for further cost savings.  The experience in Scotland suggests that housebuilders will avoid ASHP for as long as possible because customers neither like nor understand them.

3. Heat Pumps - "Lord Make Me Chaste - but not yet!"

The consultation steps away from banning gas heating in 2020, this change is timetabled for 2025.  However it does impose extra conditions on wet space heating systems to ensure that they are 'future proof'.  In practice this will mean that 'emitters' (normal people call them radiators) will be increased to a size that would work at lower temperature, and so the house would be suitable for later conversion to a heat pump heating system without the cost of replacing all the radiators.

A side effect of this requirement is that increasing the cost and space requirements for wet systems could push developers towards direct electric heating with panel heaters, simple underfloor electric or radiant heat panels.  The removal of the entire cost of the wet heating system would offset a considerable chunk of the costs for the additional measures (PV solar, more insulation) needed to stay within the householder affordability target.  A house without a wet heating system would be low on maintenance and low cost to build, coupled with better insulation plus lower cost PV and battery storage to keep bills down this could become a favoured option for new homes.

4. Transitional Arrangements

This proposed change is likely to cause significant concerns at housebuilding companies.

The current situation is that as new Building Regulations come into force, they apply only to whole developments as new planning applications are lodged with local authority planning offices and work has started on site.

The practical outcome of this rule is that new homes are still being built to versions of building regulations in force many years ago, because:

(a) Developers rush to submit planning applications in the run up to new regulations coming into force, banking large numbers of homes to be built under the old regulations
(b) Large sites of many hundreds of homes are built out over many years, but there is a site-wide application of the regulations.

This was clearly demonstrated by the 2015 Scottish building regulations change, where it is only now (nearly 4 years later) that pretty much all new sites coming forward for tender require solar.

The consultation proposes moving from a site-based application of building regulations to one based on specific buildings.  Large developments spanning many years would have to redesign to meet new building regulations that apply as the building is being built.

Housebuilders will be alarmed by this proposal because all developments still under construction under 2013 regulations will be caught in this net.  The land for these sites would have been bought at a price based on the construction costs expected under those 2013 regulations and the housebuilders will argue that this measure is a retrospective action that will harm their profitability.  How much sympathy there is for the housebuilders having to shoulder the extra costs remains to be seen, when government has been subsidising the housing market through the Help to Buy scheme and the chief executives of some companies have been given bonuses amounting to £10,000 per house built .

 5. Other Stuff

Solar PV on Apartment Blocks

 In the original SAP10, PV on apartment blocks connected to the landlords' supply did not improve the DER of the individual apartment, whereas in SAP 2012 the carbon savings were apportioned across apartments by floor area.  The Solar Trade Association argued that connection to Landlord's supply was often by far the most cost-effective and practical way to install solar on apartment blocks, that the changes would force systems to be split into mini-systems serving each apartment at great cost, and that the carbon savings were real.  It seems that this argument has prevailed as SAP 10.1 has changed the treatment of solar PV in apartment blocks back to as it was in SAP 2012. 

Heat Networks Get a Free Pass

SAP 10 introduced punitive heat losses on district heating networks, based on evidence that large amounts of heat are lost in the underground pipework of these systems (40-50% even for best practice new ones).  It seems that government thinks that heat networks will be an important part of the energy future, and that their drawbacks should be ignored.  So a fudge-factor (they call it a 'technology factor') is applied to buildings that use a heat network.  These are allowed to emit 45% more carbon for heating and 5% more primary energy.

The Government's enthusiasm for heat networks is baffling considering that there is a perfectly good electricity network that loses far lower energy in transmission and is already connected to every single property.  A heat network is not of itself low carbon - it depends what you're doing to make the heat.

The Future Homes Standard - for 2025

The second part of the consultation is some early range-finding questions for the Future Homes Standard due to come into force in 2025.

The government reckons a 70-80% reduction in carbon emissions compared to current housing is possible.  This will be achieved by adding low carbon heating (heat pump or district heating) to the Option 1 fabric proposed in the 2020 regulations, and relying on further decarbonisation of grid electricity to do the rest.  Government is seeking views on whether this is achievable.

Local authorities which have been using planning powers under the Planning and Energy Act 2008 to require developers in their region to build to standards above those of the current building regulations.  This role for local authorities has been crucial for pushing forward on energy efficiency during a period of inaction from Westminster.  The consultation considers whether these powers should be removed alongside the 2020 regulations, the 2025 Future Homes Standard or not at all.

Summary

This change is significant and there's still some modelling to be done to figure out which packages of technology developers are likely to favour, but given the simplicity and popularity of solar it seems unlikely that the technology will not be a big winner from these changes to building regulations.

Higher Standards for Housebuilders Do Not Slow Development

The Truth has Been Revealed by Scottish Developers

NOTE - a new blog with updated data is available here

Housing developers say that if you make them build more energy efficient homes, they'll cost more and less houses will be built.

Our politicians have swallowed this argument hook line and sinker time and again.

I've written about this before - the flaw in the argument is the assumption that the developers costs have to rise. They don't. This is because one of the main costs of building the house is what you pay for the land, and if everyone is faced with the same regulations, then the value of the land is driven down and the landowner makes a slightly smaller profit from the deal.

Developers have successfully held up tighter building regulations on numerous occasions.

• The update to building regulations in England in 2012 ended up as only a 7% reduction in carbon emissions (compared to the significant cut required in the original zero carbon homes policy)
• In Scotland in 2012 there was no energy efficiency improvement at all.
• The Housing Standards Review resulted in legislation in 2015 with the intent of limiting local authorities powers to require higher energy efficiency homes through planning (legislation that is still not in force).
• Finally, after 10 years of clear policy direction, one of George Osborne's last acts before disappearing off to take lucrative directorships, was to tear up the Zero Carbon Homes plan (the existence of which had been mendaciously used to justify the changes in the Housing Standards Review).

So it's very interesting to see what's been happening in Scotland. After many years of shadowing Westminster on building regulations (apart from the obvious requirement to go just a percentage point or two lower on carbon emissions to make a point), Scotland really pulled ahead with its changes to regulations in 2015.  The graph at the top of this piece shows the gap opening up.

If developers' claims that higher levels of regulation would stop housebuilding in its tracks were true, you'd expect housebuilding in Scotland to have gone off a cliff.  Has it?

Has it hell.