There is growing awareness that indoor exposure to particulate matter with diameter ≤ 2.5 μm (PM2.5) is associated with an increased risk of adverse health effects. Cooking is a key indoor source of PM2.5 and an activity conducted daily in most homes. Population scale models can predict occupant exposures to PM2.5, but these predictions are sensitive to the emission rates used. Reported emission rates are highly variable and are typically for the cooking of single ingredients and not full meals. Accordingly, there is a need to assess PM2.5 emissions from the cooking of complete meals. Mean PM2.5 emission rates and source strengths were measured for four complete meals. Temporal PM2.5 concentrations and particle size distributions were recorded using an optical particle counter (OPC), and gravimetric sampling was used to determine calibration factors. Mean emission rates and source strengths varied between 0.54—3.7 mg/min and 15—68 mg, respectively, with 95% confidence. Using a cooker hood (apparent capture efficiency > 90%) and frying in non‐stick pans were found to significantly reduce emissions. OPC calibration factors varied between 1.5 and 5.0 showing that a single value cannot be used for all meals and that gravimetric sampling is necessary when measuring PM2.5 concentrations in kitchens.

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Existing schools are badly insulated and often suffer from inadequate ventilation and cold in winter and too high temperatures in summer. Further schools nearby a busy road require high efficiency filtering, which traditionally lead to high pressure drops and installation noise. Current ventilation systems suitable for renovation often require expensive commissioning measurements and lack monitoring facilities during the use phase.With the development of the SchoolVent system we have solved these problems in an energy efficient manner. Core of the system is a balanced ventilation system with heat recovery. The heat exchanger is also used for indirect adiabatic cooling. For filtering a high efficiency and low pressure drop electrostatic filtration system is scaled up to 10.000 m3/hour. With this airflow 5 classrooms can be conditioned. The components have first been tested in the TNO laboratory. After that a pilot has been started on the Montessori Lyceum in Zeist. The main results of the monitoring during 2019/2020 are a heat recovery efficiency between 60 and 75%. With regard to the indoor climate class A of the “PvE Frisse scholen” has been achieved for summer and winter temperature and for CO2 concentration. With regard to filtration depending on the flowrate the specifications of an E10 – E11 filter have been obtained. In the climatized class rooms this lead to a 70 – 96% lower PM2.5 concentration compared to a reference classroom. The system has been further optimized with regard to installation costs and in 2021 another 14 classrooms are equipped with the SchoolVent system.

In well isolated dwellings especially with multiple residents domestic hot water (DHW) accounts often for more than 50% of the energy consumption.Currently there exist shower heat recovery units which recover 40 - 70 percent of the heat in the shower water. This efficiency can drop due to fouling of the heat exchanger, which is often not accessible. Further this is a component efficiency. The system efficiency also depends on the cooling down of the shower water due to evaporation and conduction losses to wall and floor tiles. During renovation it is often practically only possible to preheat the cold water port of the thermostat with the shower heat recovery unit. The cold water feed to the boiler would then not be preheated. In apartments it is not possible to install the highly efficient pipe-in-pipe heat exchangers as they have to be installed on the floor below the bathroom. Which only leaves shower tray heat recovery units which are in the lower range of the mentioned efficiency. In practice therefore during renovation shower heat recovery is not often applied.To address these problems a new patented concept for shower heat recovery has been developed. The Multi Energy Efficient Shower cabin (MEED) involves an insulated shower cabin (tray and walls) which is closed to minimize evaporation losses. The hot shower water is pumped up and flows over an integrated helix heat exchanger. This heat exchanger is able to extract 82% of the heat and is accessible for cleaning. In the shower cabin also an electrical 10 liter 6 kW boiler is integrated, so all cold water is preheated and directly hot water is provided which minimalizes pipeline losses. The MEED has enough capacity to shower endlessly. The MEED has been installed in existing social rental housing, private housing and in hotels. First monitoring results indicate a system efficiency of more than 70%. Aside the shower the MEED is able to provide all DHW, which makes a storage vessel superfluous. This is provides important space gain in smaller dwellings.