Supplementary Commentary to the Submission made on the SEAI Template
RIAI Comments
on the
Public Consultation Document on Dwelling Energy AssessmentProcedure ( DEAP)
12January 2011
RIAI Comments
on the
Public Consultation Document on Dwelling Energy Assessment Procedure ( DEAP)
INTRODUCTION
The RIAI welcomes the opportunity to comment on the existing DEAP software initative, taken together with the DoE/H/LG Draft Part L consultation document, weare highly supportive of the progressive and committed stance the DoEHLG has taken in making significant improvements in the energy efficiency requirements of the TGD L.
In particular, the RIAI is supportive of the ‘whole building analysis’ approach and commend the continued stance of setting overall targets for energy use and carbon emissions in buildings. This is an important opportunity to enable practitioners to choose the most cost-effective and appropriate design solutions for each particular dwelling.
- General Commentary on Adopted Approach
While acknowledging the ambitious time frame to maximise the energy efficiency of dwellings, there are substantial limitations to the current approach with the use of DEAP software.
The Irish Construction Industry has begun to embrace more ambitious targets, recognising the reality of zero carbon in the short term. As such a strong passive house movement has begun adopting principals developed in Europe, introducing much more sophisticated methodologies of calculating energy conservation, both in building fabric and services. Examination of the principles of passive house both in terms of the calculation tools and fabric detailing highlights the limitations of DEAP,
The RIAI proposes that the passive house standard is adopted in the DEAP software considering that the objective is to achieve a 60% saving, but use of the passive house standards and calculation tools is a more sustainable approach, as it naturally leads the design of a property towards a zero carbon standard. Instead the current approach may achieve the 60% saving but will potentially have to be completely abandoned in favour of totally new approaches to fabric and service design in just 3 years to achieve the zero carbon targets. Most importantly, in addition, the Passive house approach looks at the property in terms of maximising solar heat gains as the main heat source of the property which is not possible in DEAP.
- Main Proposed Amendments
2.1RIAI Proposed Amendment to MPEPC and MPCPC Methodology.
Observation:
It has been observed in practice, and demonstrated through research, that the MPEPC and MPCPC methodologies cause vastly varying levels of energy efficiency to be required of different dwellings in achieving compliance. In particular, it causes a bias against buildings with an efficient form.
Research has shown that this bias is caused by an inconsistency in the methodology used. The RIAI believe that the situation is unintentional but finds that it is highly unsatisfactory. The RIAI propose an amendment to allow this unintentional bias to be removed and ensure a fairer system of compliance.
For example, in the research, it was observed that an L-shaped bungalow achieved compliance with an energy use of 78 kWh/m2/yr, while a mid-floor apartment of the same area and volume had to achieve the much higher standard of 45 kWh/m2/yr to achieve compliance.
Additionally, because different forms and sizes of dwellings have different energy use targets, as a design progresses and changes are made, a designer is faced with a constantly shifting energy use target.
It has also come to our attention that there is no policy or regulatory requirement for the MPEPC or MPCPC. Part L defines DEAP as the tool for demonstrating compliance with the regulation. The regulation does not mention the MPEPC/MPCPC. DEAP is available for download in two formats, one of which does not contain the function to calculate MPEPC. Therefore, it is not always possible to use DEAP to demonstrate compliance which contradicts the Part L Regulation.
Proposal:
The RIAI propose replacing the MPEPC and MPCPC ratios with a fixed maximum energy use in terms of kWh/m2/yr and fixed maximum carbon emissions in terms of kgCO2/m2/yr.
Research carried out found that figures of 60kWh/m2/yr and 11.8kgCO2/m2/yr were required to demonstrate an overall improvement in building standards since 2005.
Outline of the Issue:
In order to make the comparison a ‘reference dwelling’ has been defined in the the guidance to have the standard properties of a 2005 dwelling under Part L. From this base one must demonstrate the improvement.
The reference dwelling consists of 27 parameters and these are set out in Appendix C of the TGD. It is believed, almost universally in the industry (presumably through DEAP training) that the reference dwelling measures the performance of the actual dwelling being tested under 2005 regulations. However, this is not the case.
In 2005 research was carried out to define this ‘reference dwelling’. A study of the performance of nine common housing types with 2005 regulation standards was carried out by the RIAI. It was found that on average they performed similarly to the medium size semi-detached house, and this was, therefore, chosen a the basis for a ‘reference dwelling’.
Though 24 of the parameters have been fixed, in the case of three of the parameters, the figures for the actual dwelling being tested are entered. These all relate to the form of the building.
For example, the reference dwelling always has one chimeny regardless of how many are in the actual dwelling. It always faces E/W, has natural ventilation, mains gas heating etc… Additionally the area of windows is always defined as 25% of the floor area. These parameters are all taken from the medium
semi-d described above.
However, rather than keep with the above logic and define the roof area as 50% of the total floor area (which it is in the case of the medium semi-d), the reference dwelling assumes the actual area of the roof on the dwelling being tested.
As a result, a building which is more efficiently formed, performs to a higher standard of energy efficiency in the reference dwelling, and therefore, when this level of energy use is multiplied by the MPEPC of 0.4, it is tasked with a higher target level of energy efficiency (see graph 1).
This situation is highly unsatisfactory as it penalises those who design in an efficient manner, which iscontrary to the ambition of the Part L, which is to promote energy efficient buildings.
Graph.1 - Illustrating Change in Target Energy Use of Dwellings with Different Forms
under the MPEPC Methodolog
Note that this does not require that individual dwellings demonstrate a 60% improvement on 2005 standards. This point has been confirmed by the DoEHLG. Additionally, as the reference dwelling is largely a standard house type, the MPEPC does not demonstrate improvement levels of individual houses compared to 2005 standards.
Part L Regulation.
The Part L regulation states: “For new dwellings, the requirement of L1 shall be met by providing that the energy performance of the dwelling is such as to limit the calculated primary energy consumption and related CO2 emissions … when both … are calculated using the Dwelling Energy Assessment Procedure (DEAP) published by Sustainble Enegy Ireland.”
Note that the regulation makes no mention of the use of 60% energy reduction targets or MPEPC methodologies. Compliance is to be demonstrated in terms of primary energy consumption and CO2 emissions using DEAP. DEAP measures these in terms of kWh/m2/yr and kgCO2/m2/yr.
The RIAI submit that expressing the requirement for compliance in terms of kWh/m2/yr and kgCO2/m2/yr would be more closely in keeping with the requirement in the regulation.
EPBD Building Directive.
This directive allows each country to develop their own methodology and targets, in relation to energy efficiency in buildings. Ireland’s targets are as set out in the Programme for Government and the methodology is the DEAP.
Therefore, the RIAI proposal is not in contradiction of any policy or regulatory context.
Impact on DEAP:
Currently DEAP is available for download from in two different formats. Both of them use the kWh/m2/ye and kgCO2/m2/yr measures as the primary means of calculating the energy performance of the dwelling. Only one version of the DEAP contains the MPEPC/MPCPC function.
The RIAI proposal would have little effect on DEAP as it is currently fully available without the MPEPC function, and it expresses results in the manner proposed by the RIAI.
It is submitted that the amendment would have little impact on DEAP assessors as the proposal does not add any new function. The method of presenting results would revert to being the same as in existing dwellings, so, if anything, it would make the process less complicated for assessors.
- Levels of Thermal Comfort.
There are limitations to the DEAP methodology and TGD assumptions regarding thermal comfort which must be considered. There are standard assumptions e.g. the main living space is heated to 21oc though the heating season. This could be considered quite a high temperature and the reduction of this to say 18 oc would provide a reduction in energy consumption. Currently there is no facility in DEAP to identify this as a potential energy saving measure, nor is there any examination of what constitute acceptable thermal comfort levels in dwellings within the TGD. As the standards of fabric improve the thresholds of thermal comfort will also improve. For example, as walls become well insulated the surface temperature will not be that much greater than the ambient temperature, thus the sensation of thermal comfort will be maintained at a lower temperature.
- Metric of kWh/m2/yr & C02/m2/yr
Another major limitation of DEAP and the TGD in assessing individual dwellings, in terms of energy performance, is the measure of kWh/m2/yr & to C02/m2/yr assess compliance.
Take the example of comparing House 1: 500m2 A3 rated consuming 65kWh/m2/yr and House 2: 75m2 D1 rated consuming 250kWh/m2/yr. House 1 consumes 32,500kWh/yr which is 1.7 times that of House 2 at 18,750kWh/ m2/yr yet ostensibly appears more energy efficient, which is very misleading. Very small houses should have some compensation in Part L compliance to acknowledge their actual lower energy use.
E. Renewable Technologies
The RIAI propose that the requirement for on-site renewables be altered from an absolute figure to a proportional one, i.e. that 10% of the energy demand of a dwelling is supplied by renewables.
This policy has been very successful in the UK (The Merton Rule) as it encourages a developer to construct to a standard in excess of the regulations as a means of reducing the quantity of renewables required. As it is proposed to further increase energy efficienciesof Part L in 2013, and as retrofitting is expensive and of variable success, there should exist an incentive to construct to the highest possible standards. Take the example of a Passive House: it has a maximum Energy demand of 15kWh/m2/yr without resorting to additional renewable heating measures. The principle being – reduce the heating demand through the fabric of the building, and maximize the heat gains through solar radiation and internal heat gains.
Additionally microrenewables are an expensive abatement technology and regulations which would encourage their installation in non-optimal locations should be avoided. We would recommend that renewables be required in 'all reasonable circumstances'.
Finally we would recommend that following the logic applied to solid-fuel stoves and heat pumps. They should be excluded from the list of renewable technologies because both are only partially renewable, dependent on circumstance, and therefore should be treated the same.
- Commentary on Specific TGD provisions:
New Dwellings:
1.2 Renewable Energy Technologies:
1.3Building Fabric.
1.3.1General.
This section should include further strongly worded advice making it very clear that the maximum elemental U-values are very conservative and in reality would need to be much lower to achieve the required EPC & CPC.
1.3.2Fabric Insulation.
1.3.2.4DayLight Factor.
BS 8206: Part 2: 2008 Code of Practice on Daylight.
The Daylight factors recommended here are very conservative and could result in buildings with small windows to increase the thermal efficiency but require electrical lighting on for a large proportion of the day. The BS recommends the following daylight factors:
Bedrooms / 1%Living rooms / 1.5%
Kitchens / 2%
The Chartered Institution of Building Services Engineers (CIBSE) 1987 advises that when the average Daylight Factor is less than 2%, the interior would be perceived as badly lit and artificial lighting could be utilized constantly. Instead a DF exceeding 5% on the horizontal plane is required for a room to look bright.
The current standard is undesirable both from the point of view of reducing electrical demand but also from the occupants point of view i.e. potentially dull and gloomy rooms. Provision of optimum daylight as a passive energy strategy to reduce the use of electricity should not be overlooked in the statutory design requirements of dwellings in Ireland.
Proposal: The daylight factor should be increased to 5%.
Section 4: Existing Dwellings.
4.1DEAP Review.
While the RIAI as part of the review of DEAP, has an intrinsic relationship with the Part L and it was therefore felt appropriate to make comment on several software issues in this submission.
Calculating U-Values:
The DEAP review guidance should reference acceptable software for the calculation of U-Values. As the guidance has moved away from standard U-Values, it will be less common to use the exact same U-Values from project to project, and the practitioner will have much more occasion to calculate these. Ideally the DEAP software should include a tab for recording fabric build up and calculating U-values.
Calculating Thermal Bridging:
In addition measured thermal bridges should be included as a tab within the software.
Part F Compliance:
The RIAI suggest it would be useful for DEAP to contain a tab to record details of ventilation provided and a facility to demonstrate compliance with Part F.
Thermal Comfort:
Software should enable designer to set appropriate levels of thermal comfort in terms of internal temperatures within defined parameters as part of the overall energy performance strategy.
Concluded: 12.01.2011 - RIAI
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