Air infiltration model

[jimenofonseca]

This concerns an outdoor dependent model for simualting air infiltration in buildings due to occupancy and building tightness. Until now this is generalized independently of the type of occupancy or building with the next variables in GlovalVariables.py

• self.NACH_inf_non_occ = 0.2 num air exchanges due to infiltration when no occupied. SIA
• self.NACH_inf_occ = 0.5 num air exchanges due to infiltration when occupied. SIA

[shanshanhsieh]

Instead of using fixed value as it is currently. Possible ideas: stochastic/ agent based modelling

[gabriel-happle]

Ideas: (1) Infiltration (and summer comfort) according to EN 15242:2007 (2) Infiltration analog to DOMVENT3D (http://bse.sagepub.com/content/35/4/408.full.pdf+html) (3) Annex I of ISO 13791:2012(E):

• Formula for cracks and small openings
• Formulas for large openings as function of wind and temperature differences
• how to determine area of openings??? -> occupancy and user behavior related (4) Energy performance of buildings – Part 7: Ventilation for buildings – Modules M5-1, M5-5, M5-6, M5-8 – Calculation methods for the determination of air flow rates inbuildings including infiltration; German version prEN 16798-7:2014
• still a draft; standard values missing
• successor of 15242:2007

Plan: The plan is to implement the methodology of the new standard prEN 16798-7:2014, which is part of the EPBD norms. As standard values are not yet defined for this new norm, they can be taken from the old norm instead. The implementation of occupant behavior regarding manual opening of windows is not clear yet. The first steps include:

• documentation of necessary adjustments to archetypes and building properties
• documentation of the calculation procedure and all inputs and outputs of the single steps

[adam-rysanek]

Highly advocate a detailed study / model development on this - and with a focus on handling this parameter probabilistically... Some examples: the 3for2 area infiltration is about 0.03 ACH overnight, and negative (e.g., we exfiltrate) during operational hours. Exfiltration is attributed to the creation of positive indoor pressure, which central air handling systems with fresh-air provision strive for. You can even assume that, as a norm, central air-con systems in commercial buildings have negligible infiltration during occupied hours with the exception of the ground entrance/exit floor. The 3for2 area's overnight ACH is attributed both to its tight facade and generally low wind pressures in Singapore. Residential HDBs (or even modern condos) may be significantly more leaky (as they are at my place, which is a brand new condo). However, I have found no easy rule of thumb to go by to estimate infiltration in these cases... Without better knowledge about the specific building, or some probabilistic handling, the deterministic selection of 0.05, 0.1, 0.5, 0.7 ACH for infiltration all seems arbitrary to me.....

[gabriel-happle]

This is probably continuous development. But with smaller, specific issues. I'm therefore closing this now.