Performance of natural, exhaust, demand controlled exhaust and heat recovery residential ventilation systems as prescribed by the standards in 5 European countries

Over the last decades, residential ventilation standards have been integrated in most of the buildings codes of European countries. Contrarily to the consolidation effort in the development of the nonresidential ventilation standard EN 13779, most of the residential ventilation standards have been drafted in a prescriptive way, with disparate sizing prescriptions in the different countries. Due to these differences in ventilation requirements, the reference levels for ventilation heat loss and associated indoor air quality is different in each country. The energy saving potential for demand controlled systems is therefore different in each country as well. In this paper, the performance of natural, exhaust and mechanical residential ventilation as prescribed by the standards of 5 European countries with moderate climate is assessed with regard to perceived air quality and odour spread as well as heating season integrated ventilation heat loss using multi zone simulations with local climate data. These results are then used to calculate the energy saving potential of a demand controlled exhaust ventilation system based taking into account the trade-off between indoor air quality and heat loss. With results showing that about 50% of ventilation heat loss reductions can be achieved at equivalent indoor air quality levels, we conclude that demand controlled exhaust ventilation has a good potential for reduction of building energy use in moderate climates

Performance of a demand controlled mechanical extract ventilation system for dwellings

The main aim of ventilation is to guarantee a good indoor air quality, related to the energy consumed for heating and fan(s). Active or passive heat recovery systems seem to focus on the reduction of heating consumption at the expense of fan electricity consumption and maintenance. In this study, demandcontrolled mechanical extract ventilation systems of Renson (DCV1 and DCV2), based on natural supply in the habitable rooms and mechanical extraction in the wet rooms (or even the bedrooms), was analysed for one year by means of multi-zone Contam simulations on a reference detached house and compared with standard MEV and mechanical extract ventilation systems with heat recovery (MVHR). To this end, IAQ, total energy consumption, CO2 emissions and total cost of the systems are determined. The results show that DCV systems with increased supply air flow rates or direct mechanical extract from bedrooms can significantly improve IAQ, while reducing total energy consumption compared to MEV. Applying DCV reduces primary heating energy consumption and yearly fan electricity consumption at most by 65% to 50% compared to MEV. Total operational energy costs and CO2 emissions of DCV are similar when compared to MVHR. Total costs of DCV systems over 15 years are smaller when compared to MVHR due to lower investment and maintenance costs

Passive house ventilation strategies: demand control?

Since insulation levels in a passive house context are very high, energy losses trough ventilation are of relatively high importance in the total energy balance of a passive house concept. Although fully mechanical ventilation systems are at the core of the this concept, enabling both regeneration and cheap space heating, it can still be optimized. With demand controlled systems, excess ventilation can be minimized, thus reducing both redundant ventilation losses and the accompanying electrical loads. This paper reviews the possibilities for a performance based optimization of ventilation systems for passive houses within the context of the Belgian legislatio

A comparison of different ventilation strategies for dwellings in terms of airflow rates and airflow paths

The context of ventilation in Belgian dwellings has changed since the publication of the Belgian standard NBN D 50-001:1991. Due to the higher energy performance of these dwellings, ventilation plays nowadays a more essential role in maintaining a good indoor air quality. Therefore, new rules for improved ventilation strategies are needed to accomplish high energy-efficient ventilation while providing a good indoor air quality. A first step is to compare different ventilation strategies, including strategies that don’t comply with the current standard, in terms of airflow rates and airflow paths. This comparison also includes the influence of demand controlled ventilation. This paper covers a simulation study using multi-zone airflow and contaminant transport calculation software (CONTAM) which compares the performances of the different ventilation strategies in terms of indoor air quality and average airflow rates. The evaluation of the indoor air quality is based on the exposure of the occupants to CO2 and VOC and on the relative humidity in the rooms. The different ventilation strategies can achieve a comparable indoor air quality, including the strategies not conform to the Belgian standard. However, some strategies require up to twice the airflow rate than others

Energy saving potential and repercussions on indoor air quality of demand controlled residential ventilation strategies

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Behovsstyrt ventilasjon (DCV) - krav og overlevering. Veileder for et energioptimalt og velfungerende anlegg

ForskningsrapportThe purpose of this guidebook is to help building owners to acquire well-functioning demand-controlled ventilation by applyingthe guidebook’s recommendations, as well as proper commissioning. Contractorsand property managers can use the guidebook to improve the quality of newsystems, while facility managers can use it for troubleshooting and maintenanceof existing ventilation systems. The guidebook results from the Norwegian research and development project «reDuCeVentilation» – Reduced energy use in Educational buildings with robust Demand-Controlled Ventilation. The presented solutionsare also suitable for office buildings

Hybrid Ventilation System and Soft-Sensors for Maintaining Indoor Air Quality and Thermal Comfort in Buildings

Maintaining both indoor air quality (IAQ) and thermal comfort in buildings along with optimized energy consumption is a challenging problem. This investigation presents a novel design for hybrid ventilation system enabled by predictive control and soft-sensors to achieve both IAQ and thermal comfort by combining predictive control with demand controlled ventilation (DCV). First, we show that the problem of maintaining IAQ, thermal comfort and optimal energy is a multi-objective optimization problem with competing objectives, and a predictive control approach is required to smartly control the system. This leads to many implementation challenges which are addressed by designing a hybrid ventilation scheme supported by predictive control and soft-sensors. The main idea of the hybrid ventilation system is to achieve thermal comfort by varying the ON/OFF times of the air conditioners to maintain the temperature within user-defined bands using a predictive control and IAQ is maintained using Healthbox 3.0, a DCV device. Furthermore, this study also designs soft-sensors by combining the Internet of Things (IoT)-based sensors with deep-learning tools. The hardware realization of the control and IoT prototype is also discussed. The proposed novel hybrid ventilation system and the soft-sensors are demonstrated in a real research laboratory, i.e., Center for Research in Automatic Control Engineering (C-RACE) located at Kalasalingam University, India. Our results show the perceived benefits of hybrid ventilation, predictive control, and soft-sensors

Indoor Air Quality Assessment: Comparison of Ventilation Scenarios for Retrofitting Classrooms in a Hot Climate

Current energy e ciency policies in buildings foster the promotion of energy retrofitting of the existing stock. In southern Spain, the most extensive public sector is that of educational buildings, which is especially subject to significant internal loads due to high occupancy. A large fraction of the energy retrofit strategies conducted to date have focused on energy aspects and indoor thermal comfort, repeatedly disregarding indoor air quality criteria. This research assesses indoor air quality in a school located in the Mediterranean area, with the objective of promoting di erent ventilation scenarios, based on occupancy patterns and carbon dioxide levels monitored on site. Results show that manual ventilation cannot guarantee minimum indoor quality levels following current standards. A constant ventilation based on CO2 levels allows 15% more thermal comfort hours a year to be reached, compared to CO2-based optimized demand-controlled ventilation. Nevertheless, the latter ensures 35% annual energy savings, compared to a constant CO2-based ventilation, and 37% more annual energy savings over that of a constant ventilation rate of outdoor air per person

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

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)

A novel coupling control with decision-maker and PID controller for minimizing heating energy consumption and ensuring indoor environmental quality

Due to climate change, global energy crisis, and high-quality life requirement for people, decreasing building energy consumption and enhancing indoor environment quality through control of heating, ventilation, and air conditioning systems tend to be increasingly important. Therefore, favorable control methods for heating and ventilation systems are urgently necessary. In this work, a new coupling control with decision-maker was proposed, developed, and investigated; meanwhile, several demand controlled ventilation strategies combined with heating control method was compared considering heating energy consumption, thermal comfort, and indoor air quality. In order to properly model the service systems, the air change rates and thermal time constants have been first measured in a reference office installed with commonly applied bottom-hinged tilted windows in our low-energy building supplied by geothermal district heating. Then, simulations have been carried out across two typical winter days in the reference office. The results illustrate that the proposed combination of suitable heating and demand controlled ventilation coupling control methods with decision-maker and proportional-integral-derivative (PID) controller could greatly reduce heating consumption in the reference room during the office time: around 52.4% (4.4 kW h energy saving) per day in winter in comparison to a commonly suggested method of intensive and brief airing. At the same time, it could ensure indoor CO2 concentration to keep within the pre-set ranges (Pettenkofer limit: 1000 ppm) as well as low variations of indoor temperature (standard deviation (SD): 0.1°C)