et to make London one of the greenest cities in the world, the London Environment Strategy is a blueprint for environmental excellence, detailing Sadiq Khan’s ambitious plan for London to become zero carbon by 2050. In addition to this strategy, the Greater London Authority (GLA) is setting the standard for low-carbon homes through its Housing Supplementary Planning Guidance (SPG), published in 2016.
Carbon tax
As part of this green approach, GLA is planning a carbon tax on new developments in the capital. In essence, developers must reduce the Dwelling Emission Rate (DER) of a dwelling to 35% below the Target Emission Rate (TER) required to secure a pass in Part L of the England and Wales Building Regulations. The remaining carbon, expressed in tonnes, must then be offset in the form of an abatement payment which is set by each individual borough.
The GLA recommends a price of £60 per tonne paid for 30 years or £1800 per tonne remaining. For a 200-plot development, this is an abatement payment of approximately £174,600 based on 97 tonnes remaining. This payment must be paid to the local borough at the commencement of works on the site, and the developer must submit their energy assessment to the borough as part of the planning process. Therefore, the overall energy strategy should be decided before planning permission is granted.
Reducing emissions
What does all this mean for building designers? Well, as you might expect, heating and cooling have a big part to play in the drive to reduce Dwelling Emission Rates. London’s 3.4 million homes are responsible for around one-third of London’s total greenhouse gas emissions and if these ambitious targets are to be achieved, London’s new and existing buildings “must get their heat and power (needed increasingly for cooling) from local and renewable energy sources, enabled by efficient systems such as heat networks,” says the GLA.
There are two key points here – both of which present installation opportunities for forward-thinking electrical contractors. Firstly, that we must move away from using natural gas to other energy sources, including renewable energy and the heat that is wasted from industrial and commercial processes. Secondly, that we must maximise the opportunity of local, decentralised, low-carbon energy, particularly in London, where it is particularly well suited because of the urban density. Decentralised energy ranges from small production, such as electricity from solar PV panels, to larger-scale systems based on local energy resources utilising heat pumps that supply communal or district heating or cooling through a network of underground pipes connecting it to homes and buildings.
A low temperature solution
One of the biggest opportunities lies with new apartment buildings, and there is a proven technology which can satisfy both of the points made above; heat pumps.
Compatible with decentralised systems, capable of maximising renewable energy and with an innovative new approach, heat pumps could present the ideal solution for many of the UK’s numerous new apartment buildings. And that could be good news for those building designers already working with renewable heating technologies – or indeed those looking to open up new business opportunities by doing so.
Current new-build dwellings in the UK are at risk of overheating due to a number of factors which include more stringent regulations on airtightness and fabric performance, increased living density, single-aspect apartment design and high internal gains. This risk is exacerbated in city centre multi-residential buildings, where internal gains and solar gains can be more significant due to an increased urban living density.
Overheating can, of course, be addressed using mechanical cooling via dedicated chiller plant and a chilled water network, but this often masks the symptom without addressing the cause. It also does nothing to reduce the DER, and so the financial impact of the carbon tax for London developments.
The answer could lie in using a series of water to water ‘energy loops’ within the building, as pioneered by the unique new Zeroth Energy System from Glen Dimplex Heating & Ventilation.
By creating such energy loops, designers can replace the high-temperature system with a cool, low-pressure system, maintained by the building’s central plant room. Low-temperature water flows around the building’s main loop to each apartment, which all have their own ‘mini loop’ where an individual heat pump produces chilled or heated water to the desired temperature. The water can then be passed to fan coils, which deliver cool or warm air into a room through vents in the ceiling or wall, or to underfloor heating, or smart electrical, fan-assisted wet radiators and a 180l water cylinder.
With this innovative approach, the central plant only needs to fill the balance of heating for the entire building, rather than servicing the total heating or cooling requirements of every resident at once. It is more environmentally-friendly, as less total energy is required to heat and cool the entire building, and it is far more cost-effective, the benefit of which can be passed on directly to residents.
Whilst the exact figures will vary by project due to the mix of dwelling types and differences in carbon payments required by boroughs; it is clear there are benefits to this new approach for cooling and heating using heat pumps in multi-dwelling buildings. And when you can consider that modern apartment buildings now represent more than 50% of the planned new-build housing stock in the UK, there will be ample opportunity for contractors to help realise those benefits.
