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Building Services News l July/August 2019

efficient buildings should also deliver healthy indoor air quality (IAQ). Amendments call for member states to have the dwelling’s energy balance calculation include health, IAQ and comfort levels and to address the issues of healthy indoor climate conditions in buildings undergoing major renovation. To implement the EPBD and deliver NZEB, it follows that Part L and Part F must work hand-inhand. And so it is, that in 2019, not only have these two Parts of Irish Building Regulations and their respective Technical Guidance Documents (TGDs) been updated and published together, they also have the same application date of 1 November 2019, and the same transitional arrangements. Throughout the development of the NZEB roadmap a holistic approach has been adopted, and the Technical Guidance Document has been reviewed in parallel with Part L. Following public consultation, TGD F (2019) introduces the following five notable updates and changes. 1. Natural Ventilation for NZEB TGD L 2019, states that air pressure testing should be carried out on all dwellings on all development sites introducing an improved maximum value for Air Permeability (AP) of 5 m3/(h.m2). TGD F 2019 builds on these new requirements laying out the range of validity for each of three ventilation strategies: • Centralised Continuous Mechanical Extract Ventilation (CMEV) and Mechanical Ventilation with Heat Recovery (MVHR) for dwellings should be used where the air permeability is below 3 m3/(h.m2). • Natural Ventilation (NV) can be used for dwellings where the air permeability lies between 3 and 5 m3/(h.m2).

New Part F.indd 3


Minimum performance levels for mechanical ventilation systems System type


Maximum Specific Fan Power (SFP) for continuous supply only and continuous extract only

0.6 W/litre/sec

Maximum SFP for balanced systems Minimum heat recovery efficiency

1.2 W/litre/sec1 70%

1. For balanced systems with heating coils, add 0.3 W/litre/sec

Table 1

It follows that good design practice of NV should naturally call for dwellings with a design AP of 5 m3/(h.m2) or near. Should the actual AP on-site be above that value, then corrective actions to improve the AP should be put in place. Where designing a dwelling with NV at near 3 m3/(h.m2), a good practice design approach would be to design for mechanical ventilation. Indeed, should the actual AP achieved on-site be below 3 m3/(h.m2) – easily achieved nowadays – then appropriate additional measures should be implemented to ensure adequate ventilation (TGD F 2019, 2. Mechanical Ventilation for NZEB

For the first year ever on record, 2018 saw the proportion of new

Traditional Natural Ventilation

Mechanical Ventilation

5,333 homes

5,548 homes

Figure 1: Breakdown percentage of new homes completed in 2018 with traditional Natural Ventilation and Mechanical Ventilation – Source SEAI 2018 BER database. (Courtesy of SEAI)

dwellings using mechanical ventilation outnumbering those using natural ventilation in Ireland (Figure 1)1. Reflecting this market landscape shift, a new guidance paragraph on CMEV has been added to the existing paragraphs of TGD F 2009 on MVHR and NV. Just like in TGD L 2019, we have added more compliance examples in TGD F 2019, including flow rate calculations for mechanical ventilation strategies2 for houses and apartments. TGD L 2019 provides backstop values on specific fan power and heat recovery efficiency of mechanical ventilation systems to ensure their performance will deliver energy efficiency and reduced CO2 emission (Table 1). 3. Ensuring competency in design and installation to ensure adequate, effective means of ventilation

TGD F 2019 requires for all ventilation systems in NZEB dwellings (CMEV, MVHR and NV) to be designed by competent designers, … installed, (balanced) and commissioned by competent installers3. Ireland’s training and academic providers’ network is actively designing and upping the delivery of courses to provide the training necessary at all levels of the construction industry supply chain

31/07/2019 14:57

Profile for Pat Lehane

BSNews Julu/August 2019  

Ireland's only dedicated building services journal and the official organ of CIBSE Ireland

BSNews Julu/August 2019  

Ireland's only dedicated building services journal and the official organ of CIBSE Ireland

Profile for patlehane