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Frequently Asked Questions

What are the changes in SAP 10

After years of anticipation, we are now one step closer to knowing where the construction industry will need to push to meet the next wave of energy efficiency targets.  The Building Research Establishment (BRE) has published a new SAP methodology – SAP 10.

SAP is the calculation used to work out a dwelling’s emission rate, compliance with Building Regulations, EPC scores and predicted fuel costs. It is a vital assessment for compliance with Part L and Section 6, and is also used as part of planning submissions (for energy and sustainability statements).

First and most importantly, this new SAP methodology is not yet in use, although it will eventually replace the current SAP, which has been in place since 2013. Our Building Regulations are still using SAP 2012, and there’s no news on when this will change. When Part L / Section 6 are updated, we’d expect the SAP 10 method to be adopted.

Highlighting some of the key points and changes in SAP 10, we’ve compiled a short list of all you need to know about how we’ll be building in the coming years:
1. Electric heating will be more favourable
Since the last SAP update (2012), there’s been a renaissance in the installation of wind and solar farms, giving us greener energy. So much so that the average CO2 factor from the UK’s electricity grid has halved in just six years. This means the carbon footprint of electric based heating is going to be far more favourable and could mean we start to see panel heaters becoming a favoured option for some developments.

2. On-site electricity generation will have less impact
The reduction in the CO2 factor of the electricity grid sounds like good news all round, but there is a flipside… having greener electricity means generating electricity on site isn’t going to have as big an impact as it does today. So PV systems and CHP units aren’t going to be as much help when trying to improve SAP scores.

3. Heat loss assumption for DHN will increase to 50%
Developments with district heating networks (DHN) could notice a big drop in SAP performance. Currently, default heat losses from the pipework of DHNs are assumed to be 5-20% in SAP. Going forward, a new development with no evidence of heat losses will have to assume 50%! When you consider many large inner-city schemes use DHN, CHP and PV panels, this is all going to add up to make compliance for this type of development much trickier.

4. Lower overall heat demand
To give consistent results, SAP has always worked with lots of assumptions in the background. One of these is to do with the number of hours in a day where our heating is switched on. Latest research has shown we’re in our homes less, and using our heating systems less. This will lead to lower heating demands overall. Plus, manufacturers of Wi-Fi based heating controls may be able to help improve things further if they can prove their devices mean we use our heating even less.

5. Bespoke thermal bridging encouraged
As expected, thermal bridging and fabric heat losses are being given more focus. The default thermal bridging figures are increasing by a third, which means if there are any developers still using default thermal bridging data, this is likely to push them into adopting recognised calculations. The Accredited Construction Details have been removed from SAP 10 as the ‘better case’ defaults. This is to encourage developers to research and adopt better and more specific junction details, although you’ll still be allowed to adopt ACDs if you want to.

6. Bath and shower flow rates will be considered
For the first time, SAP is going to count how many baths and showers a dwelling has, with the proposed flow rates, and whether showers are fed by electric or mains. This information will be used to more accurately work out hot water demand and could increase emissions for dwellings that are expected to use lots of water.

7. Overheating risk more likely to show on dwellings
Our lovely summer has raised the concern of overheating in our homes. SAP runs a basic check for summer overheating risks, which usually only flags up issues on heavily glazed penthouse apartments. SAP 10 is being tightened up which is likely to mean more dwellings recording an overheating risk. We’d recommend a thermal modelling assessment for a more in-depth analysis where overheating risks are anticipated.

8. Excess electricity from PV panels can be stored
A welcome addition to SAP 10 is PV storage, where excess electricity can either be sent to a battery or to heat an immersion cylinder. Currently, SAP assumes that half of the electricity generated by PVs is exported straight back to the grid.

9. Updates to reflect changes in lighting technology
Lighting technology and the efficiency of lamps has moved so fast in the last decade, that SAP hasn’t kept up. SAP 10 will record the amount and type of lamps in a dwelling. The more LED and compact fluorescent bulbs, the better result you’ll get.

What is a SAP Assessment?

Since April 2006, a SAP or Standard Assessment Procedure Calculation has been a requirement on all new build and newly converted dwellings. The SAP Calculation demonstrates that the dwelling meets the requirements of Building Regulations Part L.

To complete a SAP assessment some of the things we need to consider are:

  • the size of your house
  • heat losses through walls, roofs and windows
  • orientation
  • heating and hot water types
  • lighting
  • ventilation
  • renewable technologies

The end figure is called a Design Emission Rate (DER) which is the predicted amount of kilograms of Carbon Dioxide created by your house every year, per square metre of floor space. This figure needs to be lower than the Target Emission Rate (TER). As a rule of thumb, the TER is what your house would achieve if built to the very limits of Part L Building Regulations, less 20%.

What is a SAP Rating?

SAP stands for the Government’s Standard Assessment Procedure (SAP) for assessing the energy performance of dwellings. The indicators of the energy performance are energy consumption per unit floor area, an energy cost rating (the SAP rating), an Environmental Impact rating (based on CO2 emissions) and a Dwelling CO2 Emission Rate (DER).

The SAP rating is based on the energy costs associated with space heating, water heating, ventilation and lighting, less cost savings from energy generation technologies. It is adjusted for floor area so that it is essentially independent of dwelling size for a given built form. The SAP rating is expressed on a scale of 1 to 100, the higher the number the lower the running costs.

What is an EPC?

An EPC (Energy Performance Certificate) provides a rating for the energy efficiency of a building. The ratings are set against standard criteria to enable one building to be compared with another of a similar type. EPCs are similar to the certificates now provided with domestic appliances such as refrigerators and washing machines.

They give information on the energy performance as well as the environmental impact through carbon emissions. This information is rated on a scale of A to G, where A is the best and should have the lowest fuel bill. The average UK property is in bands D to E.

Does the Energy Performance Certificate expire?

Yes, whenever a building is constructed, sold or rented out, a certificate detailing its energy performance must be made available. This can either be to the owner or, by the owner, to the prospective buyer or tenant. No certificate may be older than 10 years.

What are Accredited Construction Details?

Accredited Construction Details (ACDs) were developed to assist the construction industry in achieving the performance standards required by Part L of the Building Regulations. The details focus on the issues of insulation continuity, with the aim to minimise thermal bridges and improve air tightness at junctions within the building envelope.

As the overall heat loss of new buildings is reduced through improved fabric standards and air tightness, the heat lost through thermal bridges at junctions represents a much higher proportion of a building’s total heat loss. ACDs therefore play an important role in lowering the impact of new buildings on the environment and also meeting ever more stringent Building Regulations’ requirements.

What are Enhanced Construction Details?

Enhanced Construction Details (ECDs) focus on heat losses that occur at the junctions between building elements and around openings. They improve on the performance delivered by the standard Accredited Construction Details (ACDs).

They are designed to help the construction industry achieve performance standards that exceed those set out in Part L1A of the Building Regulations. They also assist developers and builders to achieve the energy requirements in the Code for Sustainable Homes.

Do I need to install PV panels to pass the SAP Calculation?

Photovoltaic (PV) panels are definitely an option to consider and can provide a significant improvement in the SAP Calculation but they are not always necessary to meet the requirements of current Building Regulations. By focusing on good levels of thermal performance in the walls, floors, roofs and windows, and using efficient heating controls it is possible to meet current performance standards without the need for renewables.

Why do I get a poor rating when my building is electrically heated?

Although electric heating is 100% efficient it is very expensive compared to other fuel types. SAP Calculations take into account the cost of heating the building, therefore, the more it costs to heat the building the worse the rating will be.

The same theory applies to the DER (Dwelling Emission Rate); an electric heating system is 100% efficient but in SAP Calculations electricity is assumed to be generated by coal fires power stations, which produce high levels of CO2. As a result the calculated emissions from an electrically heated dwelling will generally be more than for a comparable gas based system.

What is an Energy Statement?

Most local authorities now expect planning applications for all new developments to be accompanied by an Energy Statement or an Energy Strategy Report. Alongside the SAP Calculations, Energy Statements or Energy Strategy Report set out how a development can reduce its predicted CO2 emissions through the use of on-site renewable and other energy sources.

Energy Statements are based on an initiative originated by Merton Borough Council to force all development to reduce reliance on the National Grid and generate site based renewable energy, known as the Merton Rule. Energy Statements usually require a development to reduce CO2 emissions onsite by 10 to 20% through the use of on-site renewable energy sources.

What is SBEM?

SBEM stands for Simplified Building Energy Model. SBEM is a computer program that provides an analysis of a commercial building's energy consumption. SBEM estimates the monthly energy use and carbon emissions of a building. iSBEM is the Interface tool for the Simplified Building Energy Model developed for CLG in compliance to the EPBD.

What does a BREEAM assessment involve?

A design stage assessment should be carried out first. There are nine categories that make up the assessment, these are:

  • Management
  • Health and Well being
  • Energy
  • Transport
  • Water
  • Materials
  • Waste
  • Land Use and Ecology
  • Pollution

Each category contains a number of individual credits, these all add up to give a final BREEAM rating. A post construction check is carried out near completion of the building and the final BREEAM certificate can be produced.

What is the Code for Sustainable Homes?

Code for Sustainable Homes is the Governments official measure of how environmentally friendly a dwelling is. The benefits of a Code rating include a higher potential income from rent/selling, reduced energy costs and a more comfortable living environment.

When do I have to provide a Water Efficiency Calculation?

Regulation 17k requires only that a notice is given to the building control body within five days of the completion of work. The notice needs to state the potential consumption. However, in practice, a copy of the completed calculation table should be submitted to the building control body.

To ensure the fittings and appliances are specified during the design stage, the Water Calculation should be completed initially and then revised if those fittings subsequently change.

What affects the projected water consumption of a dwelling?

Factors that affect the calculated water consumption of a dwelling include:

  • The flow rate of showers and taps;
  • The capacity of baths;
  • The flushing capacity of WCs;
  • The consumption per place setting of dishwashers;
  • The efficiency of water softeners (where present); and
  • Whether there is any on-site rainwater or grey water harvesting.

External taps, bath taps, swimming pools, Jacuzzis and bidets are not included in the calculation process.

Where can I find information on fittings in order to complete the water efficiency calculation?

Information can be found from manufacturers. The calculation should be based upon the data for the fittings actually installed.

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