FIELD RESULTS STAND-ALONE VENTILATION

DEPARTMENT OF ARCHITECTURE AND URBAN PLANNING

BUILDING PHYSICS, CONSTRUCTION AND SERVICES RESEARCH GROUP

WHAT DO WE EXPECT?

A good (residential) ventilation system should

reliably deliver

the needed amount of fresh air

at the location

and the time needed

EVIA TF IAQ-label

TRICKLE VENTS: AIR SUPPLY IN BEDROOMS

70% sufficiently large

Analysis: UGhent

MECHANICAL SUPPLY (MHRV SYSTEMS)

project: Clean air low energy

MECHANICAL SUPPLY (MHRV SYSTEMS)

134 |

Figuur 8-31: Overzicht van de debietmetingen in de leefruimte van de steekproefappartementen

Figuur 8-32: Overzicht van de debietmetingen in de keuken van de steekproefappartementen

MECHANICAL EXTRACTION: +- OK

Total exhaust flow rates

Max

Aver

0.75

0.25

Min

BBRI: Optivent

8

BBA Binnenmilieu, 2011

THE NETHERLANDS

AIR SUPPLY BEDROOM AIR SUPPLY MAIN BEDROOM AIR SUPPLY other BEDROOMS

Low medium high

POSITION

Low medium high

POSITION

Low medium high

POSITION

FINLAND

9

be adjustable. In buildings equipped with natural ventilation the increase in efficiency is done

by opening the windows.

The design of the ventilation systems is checked by the authorities who give the permission to

start the building process [12] (National building code). The designer needs to have

professional training level C, which is the lowest demand for the designers (A2) [12].

In practice, the air exchange rate (ACH) is typically lower than demanded in the building

code. The ACH determined from measurement of exhaust air flows is show in figure 3.

During the measurement the fan power regulator was set to the position that occupants used

during their normal living. The median of ACH was 0.38 1/h in houses equipped with

mechanical supply and exhaust ventilation and 0.40 1/h in buildings equipped with

mechanical exhaust ventilation. [13] (Vinha et al 2005). The occupants prefer to use the

lowest power in most of the houses (55%) and according to the interview of the occupant the

noise level was the main reason to keep the efficiency of ventilation on the minimum power.

It can be concluded that the design the air flow rates is not the problem, but the problem is

insufficient sound attenuation in the systems. So the design of noise control with sufficient

sound attenuation and bigger dimensions of air duct is a problem in many of the residential

ventilation systems.

Figure 2. Number of different techniques applied in the Finnish building stock [9,10].

Figure 3. Air exchange rate in wooden single family houses equipped with mechanical supply and exhaust

ventilation and with mechanical exhaust ventilation [13] (Vinha et al 2005).

PART 2

Status and perspectives

91

Vinha, 2005

FRANCE

10

Figure 4: Dysfunctions classifying per category

Statistical analysis shows that the 604 non-complying dwellings account for 1246 non-

compliance or dysfunctions points. These points directly or indirectly contribute to a bad

ventilation functioning, and also affect indoor air quality.

Figure 4 summarizes statistical results for each category. We can notice that 46%

dysfunctions are due to a bad quality of the ventilation mounting terminal devices, that are air

inlets (24%) and air outlets (22%). As for air inlets, the most frequently observed

dysfunctions are : lack of module, insufficient module quantity, and non-compliance with

characteristics of the module (airflows). And yet, on site, terminal devices comply with

specific technical terms and conditions and are delivered with plans supplied by the main

contractor. The problem lies with the quality of functional layouts mounting, often neglected.

The second important heading (around 1/3) concerns exhaust airflows. Among them, 85%

non-compliance cases are due to insufficient minimal airflows, 15% to total excessive exhaust

airflows. The frequent causes of these dysfunctions are: implementation of non-complying air

outlet, non-adapted airflows regarding the size of the dwelling, bad quality of ventilation

ducts mounting (air leakage and pressure losses).

WHY ARE THERE DYSFUNCTIONS? SOME TRACKS OF ANSWERS

In most cases, observed dysfunctions are due to lack of attention at the mounting step.

But they are also due to imperfections during the project managing process and during the

decision chain whenever the ventilation installation process is concerned. Indeed, there is a

real lack of continuity between program step, design, mounting, and also material and

component furniture.

During the execution phase, the lack of ventilation installation quality is due to the actors’

dispersion inside multiple technical lots. Thus, in the process of execution phase contracting

procedures, ventilation is rarely defined as a specific lot. As a result, the ventilation different

components installation is generally divided up among different building trades and no one

is/feels responsible for the final result.

We also observed that ventilation installation verification is rare by planned during the

construction phase, and that its control at commissioning is not systematic or most

incomplete. So, it appears that ventilation commissioning is an absolutely necessary step if

one wants to ensure a well working installation upon receipt, with an in-use performance

corresponding to the planned one. Recent guides (CETIAT, 2012)[7] describe precisely these

receipt procedures.

Securing the quality of ventilation systems

in residential buildings

20

CETE Lyon (Guyot), 2010

11

0

500

1000

1500

2000

2500

3000

Average

P 0.05

Q 1

Median

Q 3

P 0.95

0

500

1000

1500

2000

2500

3000

Average

P 0.05

Q 1

Median

Q 3

P 0.95

Living room CO2 exposure Bedroom CO2 exposure

ppm

ESTONIA

12

USER INTERACTION & MAINTENANCE

The leakage level of the envelope was measured in accordance with the pressurization method (CEN, 2001). Typical

occupancy and window opening behavior of the occupants was collected with a questionnaire after completion of the

monitoring, in order not to affect the behavior during monitoring.

Cases

The sample of cases is composed of single family houses of varying age and energy performance. Eight cases are

social housing units dating from the 60’ies, are not insulated, very leaky and have no dedicated ventilation system (group 1).

They are representative for the majority of the housing stock in Belgium. The measured annual heating demand for this

group is about 150 kWh/m2. A second group of 35 cases consists of houses of about 5 years old with standard

contemporary insulation levels, a heating demand of about 75 kWh/m2 and central exhaust ventilation systems (group2).

These dwellings are considerably less leaky. Most of the recently built dwellings in Belgium are very similar to the

specifications of the dwellings in this group. The remaining 34 cases are low energy houses (group 3), sixteen of which are

passive houses (group 4). These all have balanced central mechanical ventilation systems with heat recovery units and are

designed to heating demands of 30 and 15 kWh/m2 respectively. The low energy houses have leakage levels slightly lower

but comparable to those of the second group, while the passive houses are extremely airtight. The characteristics of these 4

groups are summarized in Table 1 and Figure 1 a).

Figure 1 Measured leakage level of the building envelope (ACH50) of the different groups in the sample (a) and

reported selected flow rate by mechanical ventilation system owners for systems with a 3-position switch in a Belgian survey

(b).

Table 1. cases

Group Number of cases Ventilation system Leakage level

1 8 none 12 ACH50

2 39 exhaust 3 ACH50 3 19 heat recovery 2 ACH50 4 16 heat recovery 0.5 ACH50

Occupancy and window airing

Since the dwellings in the first group were built by social housing programs, they are occupied by a generally older and

System out (2)

Position 1 (22)

Position 2 (7)

Position 3 (0)

regularly

sometimes

never

Of 193 respondants:

Maintenance

Manual control exhaust

BBRI Optivent (inspection)

86 ANALYSE

b. Openen van roosters

Er zijn toevoerroosters aanwezig in de ramen van de leefruimte en de

slaapkamers. Om voldoende ventilatie in de woning te verzekeren dienen

deze open te staan, ook tijdens de winterperiode. Uit de enquête blijkt

echter dat in iets meer dan de helft van de woningen de roosters in de

leefruimte gewoonlijk gesloten zijn tijdens het stookseizoen. In 40% van de

woningen blijven ook de roosters in de slaapkamers gesloten.

Figuur 3-46: Stand van de toevoerroosters afhankelijk van het soort ruimte

Door het gedrag i.v.m. het openen van roosters te combineren met het

verwarmingsgedrag van de bewoners, kunnen er vier groepen onder-

scheiden worden:

Ro 1 Roosters gesloten in elke ruimte

Ro 2 Roosters gesloten in verwarmde ruimte (leefruimte), roosters geopend in niet-verwarmde ruimte (slaapkamers)

Ro 3 Alle ruimtes worden verwarmd, roosters enkel geopend in slaapkamers

Ro 4 Roosters geopend in elke ruimte

Groep ‘Ro 4’ is de grootste groep. In iets minder dan de helft van de

woningen worden de roosters in elke ruimte opengehouden. Op de tweede

plaats komt groep ‘Ro 1’, die alle roosters sluit tijdens het stookseizoen. In

de overige vijf woningen zijn enkel de roosters in de slaapkamers geopend.

In het totaal kan gesteld worden dat 46% van de bewoners erop let dat de

roosters gesloten zijn in de verwarmde ruimtes.

Figuur 3-47: Procentuele verdeling groepen Ro1 – Ro4

c. Redenen voor het openen of sluiten van roosters

Men opent de roosters gewoonlijk voor de frisse lucht. Deze reden werd

door 69% aangehaald voor de leefruimte, en door 81% voor de

slaapkamers. 27% van de bewoners opent de roosters in de leefruimte

daarnaast voor het verwijderen van vervuilde lucht, en 8% voor het

verwijderen van condensatie. Naar de redenen voor het sluiten van de

roosters is niet expliciet gevraagd in de enquête. We vermoeden dat de

redenen gelijkaardig zijn aan de vaststellingen die eerder in het

literatuuronderzoek werden gedaan. In de winter kan de koude lucht die

naar binnen wordt gezogen als te koud worden ervaren en kan er een

onaangenaam tochtgevoel ervaren worden. Daarbijkomend zijn een groot

aantal bewoners zich niet bewust van het belang van een goede ventilatie

en zijn ze niet voldoende geïnformeerd over de correcte handelingen om

een goede ventilatie te voorzien. De koude lucht wordt dan enkel als

energieverspilling ervaren waardoor men de roosters sluit.

0%

20%

40%

60%

80%

100%

iL iSk iSo

open

gesloten

35%

11%

8%

46%

Ro 1

Ro 2

Ro 3

Ro 4

Manual control trickle vents

open all

open most

closed most

closed all

WINDOW OPENING BEHAVIOUR

14

Before sleep7% Always

closed14%

Open during day

14%

Morning open22%

Undefined36%

Always open7%

WINTER

106

205

19 34

144

196

34

378

676 690

418

599584

864

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480

720

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1200

1440

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Habits-model Weather-model Measured - Habits-model Weather-model Measured

Openin

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tio

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min

)

WINTER SUMMER

Verbruggen, 2019

POTENTIAL OF SMART VENTILATION

15

5.1.3 Ventilation levels during the year

All valves of each device have a minimum flow rate (MF) and a nominal flow rate (NF), being the maximumflow rate. During the entire day there is at least a minimum flow rate. If the sensors detect a ventilation

need, a higher flow rate will be generated. For each room, a nominal flow rate and a minimum flow rateare defined during the installation. Therefore the range between the nominal flow rate and the minimumflow rate of each room has been divided into four categories (table 5.1) to make a consistent analysis forall the rooms in all houses:

Category Description

MF Minimum flow rate

MF - 25% (NF-MF)Range between the value of the minimum flow rate and25% of the difference from the nominal and minimum flow rate

25% (NF-MF) - 50% (NF-MF)Range from 25% to 50% of the difference

between the nominal and minimum flow rate

50% (NF-MF) - 75% (NF-MF)Range between 50% and 75% of the differencebetween the nominal and minimum flow rate

75% (NF-MF) - NFRange between 75% of the difference betweenthe nominal and minimum flow rate and the nominal flow rate itself

NF Nominal flow rate

Table 5.1: Categories of ventila t ion levels

Figures 5.7-5.11 show, for each relevant room type (bedroom, kitchen, bathroom, toilet and laundryroom), the measured ventilation flow rates categorised as per the table above. Also the daily meanoutside temperature has been plotted (right-hand scale, RHS).

Figure 5.7: Levels of ventilation during the year in bedroom

35

POTENTIAL OF SMART VENTILATION

16

Figure 5.11: Levels of ventilation during the year in laundry room

This analysis was also done for the devices being ’online’ (installed and connected to the cloud) at 1 May2018 only to analyse the impact of the increasing number of devices during time (Figures 6.8-6.12 inAppendix C). Similar patterns were seen, meaning the impact of the increasing devices is neglectable inthis analysis.

To compare the ventilation of the different rooms with each other, the levels of ventilation for the differentrooms over the year and thus for an average day, are presented in figure 5.12.

Figure 5.12: Levels of ventilation for the different room types of a typical day (May 2018 to January 2019)

38

POTENTIAL OF SMART VENTILATION

17

(a) 1 toilet 1 bedroom (b) 1 toilet 2 bedrooms

(c) 1 toilet 3 bedrooms (d) 2 toilets 1 bedroom

(e) 2 toilets 2 bedrooms (f) 2 toilets 3 bedrooms

Figure 5.19: Events in toilet

There is a high occurrence of only one or two uses per day per toilet in dwellings with 1 or 2 bedrooms,whereas with dwellings with 3 bedrooms, the highest probability is three or four uses per day. The resultsfor ’1 toilet 1 bedroom’ and ’1 toilet 2 bedrooms’ are similar, and differ significantly from those for ’1 toilet3 bedrooms’. The number of devices corresponding to the group with 1 toilet and 2 bedrooms is a lotsmaller and thus less representative than the group corresponding with 1 toilet and 1 bedroom. Also it canbe there is a toilet in the bathroom too, which might affect the number of uses of the individual toilet. Alsoa dwelling with three bedrooms is the more common typology for dwellings used for families, whereasdwellings with 1 or 2 bedrooms are most used by 1/2 person(s) households. The fact that we also see a lotof uses of the toilet in the group with one bedroom only might be explained that this group contains a lotof houses with more bedrooms of which only one was equipped with a ventilation valve.

44

POTENTIAL OF SMART VENTILATION

18

5.1.2 Typical nominal flow rates per room

The standard value of the nominal flow rate is the one defined in the standard (see table 2.2) (typically 25,50 or 75 m³/h depending on the room type), but can be adapted in function of the area of the room. Wesee that in more than 90% of the cases the standard value was withheld (figure 5.6). Renson sets the

nominal flow rate in the bedrooms typically on 30 m³/h. Figure 5.6 shows the distribution of the nominalflow rate per room.

(a) Nominal flow rate in the bedrooms (b) Nominal flow rate in the kitchens

(c) Nominal flow rate in the bathrooms (d) Nominal flow rate in the toilets

(e) Nominal flow rate in the laundry rooms

Figure 5.6: Distribution of the nominal flow rate in the dataset

34

Jelle LavergeAssistant Professor

ARCHITECTURE & URBAN PLANNING

E jelle.laverge@ugent.be

T +32 9 264 37 49

architecture.ugent.be

Ghent University

@Jlaverge

Jelle Laverge