Wellhofer airtight pre-insulated attic hatch

TECHNICAL DETAILS

Current UK and IRISH Building Regulations and Method of Measurement

The most commonly used unit of measurement for airtightness in Ireland and the UK is referred to as the air permeability of a building or Q50.

To measure air permeability a pressure differential is induced onto a building using a large fan called a Blower Door. An airtightness measurement usually involves a combination of depressurising and pressuring a building to a pressure difference of 50 Pascal’s (50Pa) which is equivalent to a wind speed of about 20 miles per hour on every side of the building envelope at once, by no means an extreme pressure. Once the pressure differential reaches 50 Pa, air leakage may easily be located in the external envelope and an accurate measurement of the air permeability of the external envelope of the building is taken.

The air permeability of a building at a pressure differential of 50Pa is referred to as the Q50 of a building and is measured in m3/hr (of airflow) per m2 (of total external envelope area).

The standard upper limit level of airtightness in buildings in Ireland and the UK, is currently a Q50 of less than 10m3/hr/m2 for all new buildings. Please refer to latest edition of the building regulations for further information. A Q50 of less than 10m3/hr/m2 refers to an air permeability of less than 10m3 of air per hour per m2 of the external envelope of a building when the building is exposed to a pressure differential by depressurisation and/or pressurisation of 50 Pa. This literally means that when we exclude ventilation and design openings, and exert a pressure difference of 50 Pa on the external envelope of the building 10m3 of air per hour passes through every square metre of the external envelope.

According to the Airtightness Testing and Measurement Association (ATTMA), for airtightness best practice, buildings which are mechanically or naturally ventilated should achieve an air permeability of less than 3m3/hr/m2, this is quite a high level of airtightness.

However the highest level of airtightness required in buildings can be as low as less than 0.6m3/hr/m2, which is required in the PassivHaus Standard, which are mechanically ventilated.

As airtightness is a central part to low energy construction, it must be a priority to achieve best practice airtightness when we build, extend or renovate our buildings.

Building Energy Rating (BER)- IRELAND ONLY

The Energy Performance of Buildings Directive (EPBD) was transposed into Irish law on the 4th of January 2006. Article 7 of the EPBD requires that when a building is constructed, sold or rented, a BER detailing its energy consumption must be made available to prospective buyers or tenants. A BER gives an objective scale of comparison for the energy demand and energy performance of a building. It is rather like the miles per gallon rating for a vehicle or the A to G rating for an electrical appliance. The BER will allow prospective buyers or tenants to factor energy performance and costs into their comparison of different properties.

The BER will be expressed in terms of Kilowatt-hours per square metre floor area per year (kWh/m2/yr) and transposed graphically in the form of performance bands A1 (most energy efficient) to G (least energy efficient). The information will form the basis of a BER Certificate, the format of which can be seen on the left of this page. The BER must also be accompanied by an advisory report. The BER is valid for up to 10 years.

The BER certificate

A BER certificate means a certificate in a prescribed form on the basis of a BER Assessment, which is held and may be viewed in electronic form on the BER register, and may be reproduced and issued in printed form by or on behalf of the issuing authority (Sustainable Energy Ireland).

The Energy Performance of Buildings Directive (EPBD)

The EPBD is a piece of legislation that all European Union (EU) Member States must enact. The purpose of the EPBD is to promote improvements in the energy performance of all buildings across Europe. The complete text of the directive can be found at www.sei.ie/epbd. The principle objectives of the directive are:

*To promote the improvement of the energy performance of buildings across the EU through cost effective measures. *To promote the convergence of building standards of Member States.

The measures to be implemented in each EU member state include:

*Methodology for calculating the energy performance of buildings. *Application of performance standards for new and existing buildings. *BER schemes for buildings offered for sale or rent. *Feasibility assessment of alternative energy systems for buildings over 1000m2.

Successful implementation of the EPBD is seen as a key initiative in the implementation of the National Climate Change Strategy Ireland and to meeting EU commitments made under the Kyoto Protocol.

The Kyoto Protocol

The Kyoto Protocol is a document signed by about one hundred and eighty countries at Kyoto, Japan, in December 1997. The Protocol commits thirty-eight industrialised countries to cut their emissions of greenhouse gases. Greenhouse gases is a term used for gases like Carbon Dioxide (C02) which are mainly generated as a result of burning fossil fuels like coal, oil and petrol. Buildings are a major consumer of energy. Around 40% of final energy consumption in the EU is attributed to the buildings sector. Research has indicated that by improving the energy efficiency of buildings, CO2 emissions could be reduced by 22%.

Sustainable Energy Ireland (SEI)

SEI was set up by the government in 2002 as Ireland's national energy agency to promote and assist the development of sustainable energy. SEI in conjunction with the Department of the Environment, Heritage and Local Government (DOEHLG) and the Department of Communications, Marine and Natural Resources (DCMNR) are jointly responsible for implementing the requirements of the EPBD. SEI is responsible for publishing the national methodology adopted for assessing energy rating of dwellings as required by the EPBD.

How the BER is calculated

A BER for a dwelling is calculated using the Dwelling Energy Assessment Procedure (DEAP) published by Sustainable Energy Ireland (SEI). The DEAP is the national methodology adopted, as required, by the EPBD, for calculating the energy rating of new homes and is based on the European Standard prEN 13790. In addition it also calculates the CO2 emissions associated with dwelling energy use as required by the Amended Building Regulations 2005.

Does the BER only apply to new dwellings?

Currently yes, when a new dwelling is first occupied or offered for sale or letting (whether in writing or otherwise) if planning was sought from 1st of January 2007. However it is proposed to phase in the commencement of mandatory BER for other building types:

*1st of July 2008 - BER becomes mandatory for new buildings other than existing buildings *1st January 2009 - BER becomes mandatory for existing dwellings and other existing buildings when offered for sale or rent.

Building excempt from BER

The EPBD will apply to almost all buildings, residential and non-residential, both new and existing. However, Article 3 of S.I. No.666 pf 2006 provides exemptions for the following categories of buildings: Historical, architectural importance (protected structures), religious buildings, buildings of low occupancy or size and certain agricultural buildings.

At what stage will BER be carried out?

Persons selling dwellings off plans will be required to provide prospective buyers with a provisional BER, as calculated by registered BER Assessors. On the completion of construction of any dwelling, for which a provisional BER is generated, a BER certificate and related advisory report (which takes account of any changes implemented during its construction relative to the plans, specifications or other data on which the provisional BER was based) shall be produced to any purchaser or tenant before completion of sale or letting. As stipulated by the Amended Building Control Act 1990, section 6B (5)(a) and (b), a Building Control Authority may also request the production of a BER certificate.

What factors may affect the BER of a dwelling?

A BER is calculated using the Dwellings Energy Assessment Procedure (DEAP) and is based on the following data:

*Built form (e.g. apartment, semi-detached, detached, bungalow, etc.) *Area of house *Size of the living room area *Number of Storeys *Ventilation air leakage characteristics (e.g. chimneys, flues, fans, air leakage testing) *Types of ventilation (e.g. natural mechanical, heat recovery) *Thermal insulation (i.e. U-values of floor, walls, roof, windows and doors) *Efficiency of main space heating system (%) *Primary fuel/Heating system (e.g. gas, oil , wood pellet, etc.) *Efficiency of secondary system (%) *Emitters (e.g. radiators, underfloor heating etc.) *Heating system controls (e.g. thermostat, type of programmer, zone controls, thermostatic valves, separation of domestic hot water and space heating *Efficiency of water heater (%) *Hot water storage insulation (i.e. type and thickness) *Hot water controls *% of low energy lights

Am I required to act on proposed improvements in the BER advisory report?

No, it is up to the individual as to whether or not they carry out any of the suggested improvements listed in the advisory report.

What effect will airtightness have on the BER?

The airtightness of the external envelope will directly effect the energy rating of a building in numerous ways, depending on the method of ventilation and number of design openings (i.e. an open fire place), designed into the construction. Generally speaking, in order to achieve an efficient BER a high level of airtightness with reference to ATTMA (Airtightness testing and measurement association) best practices should be adhered to.

Can Ecological Building Systems provide guidance concerning Building Energy Ratings?

Ecological Building Systems employ qualified BER assessors. While as suppliers we do not issue certificates, we can provide insightful advice concerning achieving an efficient Building Energy Rating.

Please contact our team at Ecological Building Systems for further information.

• pro clima airtight and windtight building systems product portfolio (1.64 mb)

  A brochure showing the full air and windtight product range offered by Ecological Building Systems Ireland

• pro clima airtight and windtight building systems product portfolio (1.64 mb)

  A brochure showing the full air and windtight product range offered by Ecological Building Systems UK