Performance assessment of demand controlled ventilation controls concerning indoor VOC exposure based on a dynamic VOC emission model

I Nastase,Jelle Laverge,Arnold Janssens,S.I Tanabe,L Mazzarela,H Zhang,M.C Gameiro Da Silva,Klaas De Jonge,J Kurnitski,P Wargocki,C Inard,G Cao

doi:10.1051/e3sconf/201911101051

Abstract

The performance assessment of ventilation systems often focusses only on CO2 and humidity levels. The indoor Volatile Organic Compounds (VOC) emissions of building materials or other products is thereby overlooked. The new generation of ventilation systems, Demand Controlled Ventilation (DCV), are systems that do not supply the nominal airflow continuously but are controlled by CO2 or humidity sensors in order to save energy. This poses potential problems for exposure to VOCs. In this study, a dynamic VOC model, which takes into account changing temperature and humidity that was derived from literature, is implemented in a CONTAM model of the Belgian reference apartment. The impact of a DCV system on the indoor VOC levels is investigated. Results show that the use of a dynamic model is necessary compared to the previously used approximation of a constant emission. Furthermore, on a system level, the influence of the ventilation system control on the indoor VOC levels shows. The overall VOC concentration in the different rooms will be higher because of lowered ventilation rates. Especially in rooms that are often unoccupied during the day, the accumulation of VOCs shows. In the development of DCV system controls, the aspect of VOC exposure should not be overlooked to be able to benefit from both the energy savings and improved Indoor Air Quality (IAQ).

Highlights

In the performance assessment of Demand Controlled Systems (DCV), often, only the CO2 level and humidity are evaluated as they are indicators of comfort
The results of the simulations support the need for a dynamic Volatile Organic Compounds (VOC) emission model
For all cases, using a constant emission model would lead to biased results about the real VOC concentrations and will lead to an inaccurate assessment of the examined ventilation system

Summary

Introduction

In the performance assessment of Demand Controlled Systems (DCV), often, only the CO2 level and humidity are evaluated as they are indicators of comfort. It is well known that building materials, furniture and many other products emit Volatile Organic Compounds (VOCs) depending on temperature, humidity and age. These emissions can potentially result in long exposure to concentrations exceeding health guidelines. VOCs are typically taken into account by assuming constant emissions based on the emission rate after 3, 7 or 28 days in a small-chamber emission test [3]. This gives a misrepresentation of real VOC emissions and VOC concentrations in the indoor environment. A temperature, humidity and time dependent model for the emissions of formaldehyde from Medium-Density Fiberboard (MDF) was used in this research to represent VOC emissions from indoor sources[4]

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Results

Discussion

Conclusion