A commercial office development

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Description of fictional building

A 5 storey office building is proposed in a city centre location. A biomass (wood pellet) boiler is proposed to meet the RSS ENV5.B3 policy requirements.

Baseline energy use and CO2 emissions

Energy use = 2,434,055 kWh/yr

CO2 emissions = 902,971 kgCO2/yr

Energy use and CO2 emissions figures calculated using Part L 2006 NCM methodology via iSBEM software..

Things to check:

• Is baseline energy use calculated using approved software?
• Does baseline energy use include unregulated electrical energy use (excluding process or catering loads)?
• Are Part L fuel emission factors used?

Requirements of Part L 2006

Part L 2006 sets out minimum levels of insulation and heating/lighting efficiencies for new homes but also requires the expected regulated CO2 emissions (the BER or Building Emission Rate) to be calculated and for it to be lower than a Target Emissions Rate (TER) set by Part L.

The new office has high efficiency heating, cooling and lighting and uses a high efficiency biomass (wood pellet) boiler to provide heating and hot water.

TER = 26.47 kgCO2/m_/yr

BER = 17.92 kgCO2/m_/yr

Figures calculated using Part L 2006 methodology via iSBEM software.

Revisions to Part L in 2010 and beyond

Part L will be revised in 2010 with a 25% improvement in CO2 emissions required over current standards. This will increase again in 2013 and in 2016 new homes will need to be net zero carbon. This will require increased use of DLZCTs to meet these tougher carbon emission standards.

Things to check:

• BER is lower than TER? This can be with or without DRLCTs for Part L requirements but only covers regulated emissions.

Requirements of BREEAM Offices 2008

BREEAM 2008 has mandatory CO2 emissions (Ene1) requirements for Excellent and Outstanding ratings measured via the Energy Performance Certificate (EPC) and additional credits can be obtained for carbon emission reductions from low carbon technologies (Ene5).

Ene1: Office achieves an achieves an EPC score of 32 with the biomass boiler, this is sufficient for the Excellent rating mandatory level and 7 credits.

Ene5: The biomass boiler reduces CO2 emissions by 42,179 kgCO2/yr. This is a 12.1% saving on the BER (regulated emissions) but only a 4.7%. Saving on total emissions (including unregulated electrical energy use). This is therefore not sufficient for 1 Ene 5 credit.

Things to check:

• Calculations (SBEM calculations showing BERs) are provided both with DRLCTs (for Part L and BREEAM Ene 1 credits) and without DRLCTs (for evidence for BREEAM Ene5 credits).
• For BREEAM Ene 5 credits all savings are in terms of total carbon emissions (kgCO2/yr) including unregulated electrical energy use (excluding process or catering loads)?

Requirements of RSS policy ENV5.B3

RSS ENV5 policy B3 requires new developments of more than 10 dwellings or 1000m_ of non-residential floorspace to secure at least 10% of their energy from decentralised and renewable or low-carbon sources, unless this is not feasible or viable

Evidence (SBEM calculations showing the energy use with and without biomass boiler) shows that the biomass boiler provides 249,581 kWh/yr or 10.3% of total energy (including unregulated energy uses).

It should be noted that biomass and other renewable or low carbon heat sources can provides 10% energy but less than 10% carbon as in this case. For technologies which generate electricity (solar PV and wind turbines) the opposite is true and so evidence that these technologies provide 10% carbon savings is not sufficient for the RSS policy as this does not guarantee 10% energy savings.

Things to check:

• Calculations (SBEM calculations showing energy use) are provided both with and without DRLCTs (to enable compliance with RSS policy to be shown).
• Savings are in terms of total energy requirement (kWh/yr) including appliances and cooking.

Other passive design and energy efficiency solutions

It should be noted that other passive design and energy efficiency measures such as increased insulation or higher efficiency boilers may be more cost effective ways of saving energy and carbon. This will help with Part L compliance and BREEAM Ene1 credits but are separate to the requirements of RSS ENV5.B3 which requires a more decentralised approach to renewable energy and is not only about reducing carbon emissions.

Other decentralised and Renewable or Low Carbon Technology (DRLCTs) solutions

There are a number of decentralised and renewable and low carbon technologies which could meet the RSS ENV5.B3 requirements for a single home. This example used biomass boilers but other solutions are available and may be more suitable for specific sites.

Things to check:

• Energy supplies are from decentralised and renewable or low carbon technologies and not from passive design and energy efficiency measures.