Appendix 1. Building codes and the EPBD
National building codes
In general terms the National building codes, for non-domestic buildings, all take the same approach in that they set:
- Minimum (or backstop) requirements for:
- Fabric elements (doors, windows, roofs, floors, walls etc.) – normally in terms of U-values and in some cases Km (Kappa-m) are used. For example in Germany all the major building elements have limiting U-value and those containing glazing have transmittance values as well. Table 1 summarises the U values (in W/m2K) for each of the countries in terms of the major building elements. The project should aim for the best performance of each of these elements where ever possible.
- For building services, a variety of metrics are used with the most common being for heating - The Effective Heat Generating Seasonal Efficiency; whilst for cooling a combination of Seasonal Energy Efficiency Ratio (SEER) and nominal energy efficiency ratio (EER) for the cooling generator. For example the UK has all its services and their backstop performance values in a separate Non-Domestic Building Services Compliance Guide. Another approach has been to group all the services providing conditioning together (e.g. Poland) and give them an overall performance target in kWh/m2. However this approach is a half-way house in that it does not deal with the specification of individual pieces of kit, neither does it deal with the performance of the building as a whole.
- For controls, minimum functionality is specified and none of the building codes, except the UK which was recently updated in November 2013, reference the new European standard BS EN 15232:2012, which will be discussed in the next section.
- Climate zones are defined if there is sufficient variation over a country, for example Italy has six climatic zones, each zone with their own set of minimum u-values for building fabric elements.
- In addition to the climatic zones overheating calculations and conditions are included in several of the codes (for Hungary), which are essential in minimising the peak service load and thus the energy efficiency of the building.
- For Renewable Energy Systems, there are no minimum performance requirements but the contribution of the technology to the reduction of carbon emissions is recognised, normally through a calculation methodology. Some countries have a minimum renewable contribution, for example Spain has a minimum solar contribution for hot sanitary water and minimum photovoltaic contribution for electric power.
- In the majority of cases the building code requires the calculation of an overall energy performance (an asset rating) which is compared to a minimum performance level. The building has to pass this test to be compliant. This calculation is either done at the design stage or at handover, or both. Both would seem to be the most sensible where the design is checked to be compliant and so is the building as-built; thus ensuring what is designed is delivered. This can be terms of primary energy or estimated usage or both; for example Hungary have Total primary energy: [kWh/m2/annum] where maximum permitted values are set, in consideration of A/V ratio and function (residential, office, educational, other) of the building. (“A” is the sum of the surfaces (walls + windows + roof + floor) around the heated air volume, and “V” is the heated air volume).
- A more refined approach would be where both primary energy (that supplied to building including renewables) and energy usage (that used in servicing the building) are considered separately.
The weakness of an approach based on minimum requirements is that it does not encourage best practice in terms of the technologies used and their individual performance. However, other policy vehicles such as market transformation programmes, financial incentives, and public procurement programmes, have been used in several European countries to drive improvement in the sustainability of non-domestic buildings and their components whilst reducing their environmental impact, including energy usage.
An advantage of having compliance software is that suggested technologies can be modelled to determine their potential energy saving potential. However, not all technologies can be modelled this way because the software normally assumes “standard conditions”, i.e. all buildings of the same type have the same hours of occupancy and occupancy density.
An example is high energy performance controls systems which improve the energy performance of non-domestic buildings by advanced control functions, e.g. adaptive cooling set points and ventilation related to the number of occupants. The performance of these and simpler controls can be assessed by BS EN 15232:2012 which has a series of classes describing the energy performance – see Figure 1. This overall energy performance (an asset rating) is normally made more stringent with every new version of the non-domestic building code thus driving minimum standards up over a period of time.
Typical occupancy patterns are provided in BS EN 15232 for a range of non-domestic building types; it defines classes of energy efficient controls which can obtain that degree of control.
Figure 2 shows the standard operational characteristics of buildings, where there is a small difference between heating and cooling temperature set point, is typical of control packages defined under the building codes and does not optimise the energy performance of the building.. The operation of all HVAC systems starts two hours before occupancy and finishes three hours after occupied period is ended. This control set up is not considered to be energy efficient as there is no need to maintain comfort conditions for three hours after occupancy.
Figure 3 shows how a high energy performance controls systems improves the energy performance by advanced control functions, e.g. adaptive cooling set points and ventilation related to the number of occupants. A Programmable BEMS would normally be required to realise the potential savings from a Class A control system.
In order to model and estimate the potential savings from control systems Dynamic Simulation Models (DSMs) are required or indicative savings can be estimated from the tables in the standard. Building controls and their specification is further discussed in section 4.6 of Deliverable 2.1 from Ecoshopping project.
The European Building Automation and Controls Association (eu.bac) has a certification scheme based on BS EN 15232. The purpose of this scheme is to ensure that a system’s extensive features and functionality in terms of energy-saving measures are installed and used to their full potential over the lifetime of the system.
Energy Performance Building Directive (EPBD)
In some cases the software producing the EPC is the same as that used for building code compliance which means that the results are comparable in terms of the rating. Unfortunately, this not always the case especially when the EPC is an operational rating, based on meter readings, where direct comparison is not possible; an exception is in the UK where the Green Deal tool can be used to join up the asset and operational ratings of non-domestic buildings.
In addition, the recast of the EPBD has further requirements:
- From Article 2 of the Recast:
10. ‘major renovation’ means the renovation of a building where: (a) the total cost of the renovation relating to the building envelope or the technical building systems is higher than 25 % of the value of the building, excluding the value of the land upon which the building is situated; or (b) more than 25 % of the surface of the building envelope undergoes renovation; Member States may choose to apply option (a) or (b).
- Article 7 however, leaves the door open for elemental requirements
Member States shall take the necessary measures to ensure that when buildings undergo major renovation, the energy performance of the building or the renovated part thereof is upgraded in order to meet minimum energy performance requirements set in accordance with Article 4 in so far as this is technically, functionally and economically feasible. Those requirements shall be applied to the renovated building or building unit as a whole. Additionally or alternatively, requirements may be applied to the renovated building elements.
- Article 4 says that the requirements shall be cost-optimal.
The implementation of these requirements has yet to be clarified and as a result it is unclear whether the national building codes for non-domestic buildings are compliant with the EPBD.
The other weakness with the Energy Performance Certification is that unlike other products no attempt has so far been made to drive the market upward. With other products the lower classes have gradually been phased out over a period of time; for example for domestic appliances, such as washing machines, the only appliances now commonly available are A and A* rated appliances.
The only member state (MS) to move in this direction is the UK where Landlords of commercial premises will be unable to let properties that fall below a set level of energy efficiency unless they make certain improvements. The level of energy efficiency will be demonstrated by the property’s EPC and the intention is for this to be set at EPC rating ‘E’. The rule is to be brought into force by 1 April 2018 by enacting it through the Energy Act of 2011.