The NHER scale has been extended to be a 0-20 scale to take account of the fact that modern houses often reached 10 on the old scale. NHER 20 represents zero total fuel costs, which is a very demanding target.

The UK government recently announced its goal that all new homes will be 'zero carbon' by 2016. NHER software is the perfect tool for pursuing this goal, given that the NHER and associated CO2 emissions are based upon the total energy consumption of a dwelling.

NHER 20 is a highly ambitious target. It can only be achieved in a dwelling which generates sufficient income from generated energy to offset unavoidable fuel costs and standing charges. To reach NHER 20 in a dwelling that meets the Energy Saving Trust Advanced Standard Fabric measures with 4 square metres of solar thermalpanels supplying hot water would require the generation of around 30GJ of electricity, which is equivalent to 10kWp of PV (around 90m2) or a 6kW wind turbine on a fairly windy site. It would not be possible to even contemplate this without first taking steps to reduce electricity consumption through low energy appliances. It will be possible in a future release of NHER Plan Assessor to model these.

Below you can find information on how to achieve various NHER ratings above 10, and a copy of the NHER Cost Table.

NHER 10.0 corresponds to the 2006 Building Regulations standard for England and Wales for a gas heated home.

NHER 11.0 is a good initial target for developers wishing to go beyond the Building Regulations.This can be achieved in England and Wales for a gas heated home with the EST Best Practice Standard, possibly with the inclusion of solar water heating. In Scotland, it would require the EST Advanced Standard Fabric Measures rather than Best Practice Standard, and in Northern Ireland onsite electricity generation as well. This corresponds roughly to the Code for Sustainable Homes Level 4.

NHER 14.0 Onsite electricity generation is essential if higher NHER values are to be achieved. It is just about possible to achieve NHER 14.0 with roof-mounted PV.

NHER 20.0 is a highly ambitious target, which will require technological innovation and shifts in the pricing mechanism for onsite electricity generation. NHER ratings of 20 can currently only be achieved by additionally including offsite generation of electricity. The NHER will eventually be made sensitive to the efficiency of fixed appliances, so that the provision by developers of appliances with high-energy labels will also contribute to raising the NHER.

Zero Carbon is much easier than NHER 20. This is because technologies that deliver low carbon have fuel cost penalties associated with them, and so reduce the NHER. For example:

• Wood pellets are very low in carbon emissions, but have a relatively high cost per kWh.
• Electricity generated onsite from PV or from wind power generates similar levels of CO2 reduction regardless of the relative proportion of electricity used and exported. The cost saving of exported electricity is however a third of the saving from electricity consumed onsite. The assumptions made about the pence per unit received for exported electricity and about the percentage that is used within the dwelling make a huge difference to the resulting NHER and associated running costs.

Reaching Zero Carbon by 2016 NHER software has a crucial role to play in meeting the Government's aim of having all new housing be zero carbon by 2016. It is the only commercial software that produces estimates of total carbon emissions and total dwelling running costs. The carbon-based levels of the Code for Sustainable Homes will be the framework for new house design from now onwards, in England and Wales at least. The NHER software provides NHER Assessors with a way of demonstrating compliance with Level 6 of the Code by providing total CO2/year and total CO2/year/m2 as standard outputs. This is not possible with SAP based software, as these do not consider fuel usage by appliances and their interaction with the space-heating requirement.

Why invest in a low carbon home? The NHER rating itself also has a key role to play in providing a way of communicating the financial benefits to the householder arising from living in a low carbon house. The NHER Cost Table provides a developer/estate agent with a way of providing prospective purchasers with an estimate of the running cost of any home issued with an NHER rating.

Affordable Housing and Fuel Poverty The NHER also has much to contribute to the debate on affordable housing, which is about much more than building cheap housing. Again, the NHER Cost Table can help assess whether the home is truly affordable by bringing fuel running costs into the debate. NHER software also has a key role in helping to tackle fuel poverty. The NHER rating continues to be used in Scotland as a way of satisfying the Housing Quality Standard.

Click here to download the full 'Getting to NHER 20' document.

The NHER Cost Table provides estate agents, developers and prospective purchasers a way of estimating the total fuel running costs of a dwelling, from the NHER of a property and the floor area.

Click here to download the NHER Cost Table.