Ventilation and heating in Passivhaus schools

[David OLIVIER]

Worth noting that if rads are used, there's little or no case for intermittent heating, for all the (I hope) well-known reasons.

D

[Andy Simmonds]

DOUG
NEXT TIME IM UP A LADDER NEAR THE TERMINAL I WILL HAVE A LOOK!

[Dave Howorth]

I wrote:

I came across a paper that may be relevant:

Ventilation and health in non-industrial indoor environments: report from a European Multidisciplinary Scientific Consensus Meeting (EUROVEN)

P. Wargocki et al

Indoor Air, Volume 12 Issue 2, Pages 113 - 128

I've now received permission to post some of the content. Here's the abstract, some snippets that I found particularly interesting, and the conclusions:

Abstract

Scientific literature on the effects of ventilation on health, comfort, and productivity in non-industrial indoor environments (offices, schools, homes, etc.) has been reviewed by a multidisciplinary group of European scientists, called EUROVEN, with expertise in medicine, epidemiology, toxicology, and engineering. The group reviewed 105 papers published in peer-reviewed scientific journals and judged 30 as conclusive, providing sufficient information on ventilation, health effects, data processing, and reporting, 14 as providing relevant background information on the issue, 43 as relevant but non-informative or inconclusive, and 18 as irrelevant for the issue discussed. Based on the data in papers judged conclusive, the group agreed that ventilation is strongly associated with comfort (perceived air quality) and health [Sick Building Syndrome (SBS) symptoms, inflammation, infections, asthma, allergy, short-term sick leave], and that an association between ventilation and productivity (performance of office work) is indicated.
The group also concluded that increasing outdoor air supply rates in non-industrial environments improves perceived air quality; that outdoor air supply rates below 25 l/s per person increase the risk of SBS symptoms, increase short-term sick leave, and decrease productivity among occupants of office buildings; and that ventilation rates above 0.5 air changes per hour (h−1) in homes reduce infestation of house dust mites in Nordic countries. The group concluded additionally that the literature indicates that in buildings with air-conditioning systems there may be an increased risk of SBS symptoms compared with naturally or mechanically ventilated buildings, and that improper maintenance, design, and functioning of air-conditioning systems contributes to increased prevalence of SBS symptoms.

Snippets

"it was concluded that outdoor air supply rates below 25 l/s per person in offices can increase the risk of health and comfort problems and can reduce productivity, and that a similar relation is likely for schools. Furthermore, the studies judged conclusive showed that air change rates below 0.5 h)1 in homes in Nordic countries can increase the rate of infestation of house dust mites. As a causal relationship exists between house dust mite infestation and allergy (Andersen and Korsgaard, 1986), these data imply that low ventilation rates in homes may be one of the factors exacerbating allergies."

"This concerns especially schools and homes where fewest studies were carried out. Reviewed articles showed very poor conditions indoors, especially as regards ventilation in schools, many of which had ventilation rates far below the requirements in ventilation guidelines and standards"

"It is important for future investigations to determine why occupants of air-conditioned buildings suffer more often from SBS symptoms than occupants in naturally or mechanically ventilated buildings."

"In general, there is a lack of data allowing sound comparisons to be made of naturally, mechanically, and air-conditioned buildings; there is an urgent need for more studies in these buildings, including subjective measurements and sufficient characterization of indoor climate."

Conclusions

The following consensus was reached by the EUROVENgroup:

• The literature shows a strong association between ventilation and comfort (as indicated by perceived air quality) and health (as indicated by SBS symptoms, inflammation, infections, asthma, allergy, short-term sick leave). It also indicates that there is an association between ventilation rate and productivity (as indicated by performance of office work).

• The literature indicates that outdoor air rates below 25 l/s per person in offices increase the risk of SBS symptoms, increase short-term sick leave, and decrease productivity. They also suggest that the same may apply for schools but little information on this aspect is available at present.

• The literature indicates that air change rates above 0.5 h)1 in homes reduce the degree of infestation of house dust mites in Nordic countries. Taking into account the causal link between house dust mites infestation and asthma and allergies, these data suggest that decreased ventilation may exacerbate allergies.

• The literature indicates that occupants of many buildings with air-conditioning systems may have an increased risk of SBS symptoms compared with occupants in naturally or mechanically ventilated buildings, implying thus that new ways of conditioning the air may be required. These results could be confounded by a number of factors such as improper maintenance of HVAC systems (the more complex the system the more liable it is to fail), building age (new types of building material are likely to be found in air-conditioned buildings erected in the past 30 years), and unknown factors such as window opening. The  studies were furthermore carried out mainly in transient and cold seasons, without taking into account the thermal benefits of air-conditioning in hot seasons.

• The literature shows that improper maintenance, design, and functioning of HVAC systems contributes to an increased prevalence of SBS symptoms. This indicates a need for safety factors and proper maintenance of ventilation systems, including such aspects as appropriate distance separating the inlet and exhaust, replacing dirty filters, cleaning ducts, and the prevention of water reservoirs and water in the systems.

• The literature shows that pollution sources other than the pollutants emitted by humans (bioeffluents) are important indoors. Consequently, proper source control is required in the first place, and secondly the design of ventilation rates based on all pollution loads present indoors.

• The present work indicates the gaps where knowledge is lacking as regards the effects of ventilation on human health, comfort, and productivity. More information is required on links between ventilation rates and health in schools and homes, and on the association between type of ventilation system and health effects.

Cheers, Dave

[Dave Howorth]

Another document that I came across was a recent report by the NHBC Foundation.

crump et al - Indoor Air Quality in highly energy efficient homes

http://www.nhbcfoundation.org/LinkClick.aspx?fileticket=O2KJ3j%2FSnkM%3D&tabid=339&mid=774&language=en-US

[Mr Ian J Armstrong]

Haven't got through all of the entries on this one but as a first time on the forum, it occurs to me that  pupils especially the youngest are often at the mercy of teaching staff or property maintenance folks when it comes to temperature, air and even light quality. How many times do we enter school classroms to find them with displays over windows, heating turned up , doors open etc 

Much of what we do is to talk to the staff and children about the designs of thir school buildings, the reasoning and the operation. We place a fair bit of emphasis on seeing that the operation manuals we issue at handover are shared and understoood as far as possible with the people that are going to control these aspects.

For the record, I have a great deal of time for the principle of PH but I urge everyone out there involved with number crunching to make time for good basic design principles,  consider buildings which will inspire our young and give full consideration to the inate problem / opportunity of people having control over their environments.

At this point I'm probably not not making much more sense but hopefully something here may strike a chord.


Martin Penk (Ians Colleague at ARCO2)

[Nick Grant]

Hi Martin

Good points. Interestingly the PH approach does leed to simplifications and the single classroom radiator with its own TRV is a good example. If it is accidentally left off the room won't drop much below 18C anyway so no need for sophisticated BMS backup with user override, just a simple control on the radiator.

My own view is that in very low energy buildings, control becomes less of an issue as the environment is comfortable. Being able to control temperature and ventilation becomes much more of an issue when these are regularly uncomfortable as is often the case in schools and offices I have visited.

Nick