the solarblogger: Owner Occupiers – Government’s Final Frontier for Energy Efficient Buildings

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Dutch Householders Must Now Include Renewables When Making Major Home Improvements
Image (C) Viridian Solar

UK energy efficiency laws have been made for new homes and new commercial buildings, for houses owned by private landlords (in England) and those managed by Social Housing  Providers (in Scotland), but the biggest part of the building stock has so far sailed on without interference from lawmakers in the UK – those owned by private individuals.

Unlike owner-occupiers; house-building companies, local authorities and social landlords don’t get to cast a vote in a general election, making them easier targets for potentially costly or unpopular new laws.  When David Cameron’s celebrated coalition government put forward an idea to require improvements to energy efficiency alongside home renovations called ‘Consequential Improvements’ in 2012 it survived only a few days after being  dubbed the ‘Conservatory Tax’ by the Daily Mail.  

See also this post from 2013 on the death of the Consequential Improvements idea.

If you are doing building works on your home, the current building regulations apply to the new bits you build, so any new walls and roofs would be insulated to modern levels.  The idea of the Consequential Improvements proposals was that (subject to the work exceeding a threshold of size) you should also have an obligation to make energy efficiency improvements to other parts of the building (for example topping up loft insulation or installing an efficient boiler or solar panels).

Looked at from the perspective of today, with occupants of inefficient housing most exposed to rampant energy cost inflation it certainly looks like a missed opportunity.  Hooray for the Daily Mail – a genuine force for good and yet again, as so often, on the right side of history!  Householders were freed from having to pay “hundreds of pounds extra on energy efficiency when they build an extension or fit a new boiler” in return for the privilege of paying thousands of pounds extra every year for soaring energy bills.

10 Years Later, in The Netherlands

Across the North Sea, the Netherlands government has brought in something that looks uncannily like the UK proposals of 10 years ago.

From February 1, 2022 an update to the “Bouwbesluit 2012” (Building Decree) regulations  place a requirement on renovation projects in Netherlands to include renewable energy.

Only renovation projects that meet both of the following requirements fall under the new rules:

 (a) more than 25% of the external envelope (ground floor, walls and roof) of the building is changed, and

(b) a heating or cooling system is part of the renovation – for example changing a central heating boiler, or replacing a third or more of the radiators.

The law applies to both housing and non-domestic properties. 

If a renovation falls under the new rules then renewable energy must be installed.  The amount you should install is derived from a formula which specifies the amount of renewable energy per year the system should yield:

30 x Aroof / Ag  kWh/m2.yr  (subject to a maximum of 30kWh/m2.yr)

Aroof is the roof area and Ag the “Gebruiksoppervlak” (usable floor area) as defined in NTA 8800:2020+A1:2020

So taking the example of a house with 100m2 of total usable floor area split in the typical Dutch style over ground floor and first floor in the roof , say 60 m2 to ground and 40 m2 to first floors together with a roof pitch of 45 degrees.  By trigonometry, the roof area is 1.41 x the ground floor area – 84.6 m2.  The calculated annual renewable energy is 30 x 84.6/100 = 25.4 kWh/m2.yr, or 2,540kWh/year in total when multiplied by the 100m2 total floor area.

This quantity of renewable energy production is very easily met with solar – around 3kWp would do it.

Certain exemptions are possible.  If you can show that the measures to meet the requirement would have a payback longer than 10 years, then you can install a smaller amount that does pay back in under this time.  Buildings with an occupancy type with very low energy use are exempt.  Finally buildings with special circumstances such as monumental buildings can be exempt from the requirement altogether if their protected status prevents the installation of measures.

The building owner has a choice of options to meet the requirement – for example joining a heat network, solar PV or installing a heat pump.  For solar PV, the Dutch government has helpfully provided a solar calculator to determine how much Solar PV is needed, based on NTA 8800:2020+A1:2020, a standard providing a method for the determination of energy use in buildings.   The solar calculation is from Chapter 16 of NTA 8800 and takes the installation details into account (orientation, shading, etc…).

In most cases the requirement for solar PV works out at between 15 and 20% of the roof surface area.  For example: Using  Clearline fusion PV16-335-G1 roof integrated solar panels (which are classed as ‘moderately ventilated’ because the air gap behind the panels exceeds 100mm); on a South facing orientation; on a 35⁰ pitched non-shaded roof; on a building of 100m2, you would need 8 panels to meet the requirement.

From the point of view of the solar industry, which offers a simple, proven and low-cost way to comply with the renewable requirement, this is a welcome change that ought to result in a good deal more solar PV on homes in the Netherlands.  

Looking at the requirements more critically through the lens of energy efficiency it does strike me a somewhat one-dimensional.  Why not require changes that improve fabric efficiency – thermal insulation and draft-proofing as well?  Perhaps the Netherlands building stock is more air tight and better insulated than that in the UK, but I’d be very surprised if there isn’t lots of stock that could also benefit from improvements in this area.  The ‘fabric first’ brigade in NL must be looking for their pitchforks and burning torches.

The new renewables obligation in the Dutch Bouwbesluit 2012 does have the advantage of being very simple to calculate, implement and install.  Perhaps it’s an example of pragmatic legislation that doesn’t letting the perfect become the enemy of the good?  Just getting on and doing something to make a difference!  Is there a Dutch equivalent of the Daily Mail?  Where was it when it was needed to stamp all over a progressive and practical idea for improving the world?

 



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