El indicio

Ventilation relies on the movement of air into and out of the building and ventilation rates are calculated according to the size of openings provided for this purpose. As air passes through the building it will encounter some resistance, the level of which will depend on the layout of the internal spaces. Therefore, it is important to minimise obstructions to the intended ventilation path to maintain adequate airflow rates (Mumovic and Santamouris, 2013).

Vents

The inlet vents at Case A are located in the walls and not, as is more conventional, in the window frames. Several vents at this case were found to be obstructed by pieces of furniture.

For example, in Ali’s house, a bookshelf has been fitted in front of the wall vent in his daughter’s bedroom (Figure 46). He complains that ‘all the bad smells in the house seem to hang out here’, which might be connected to the obstructed vent. Another example in this dwelling is the wardrobe in the master bedroom which is also positioned in front of the wall inlet, potentially obstructing the airflow to and from it (Figure 46).

At Karen’s house, the master bedroom furniture has also been installed in such a way that the wall inlet is blocked by one of the wardrobes, and access to the main windows is also obstructed (Figure 47). In another room in the house, a child’s bunk bed had been recently replaced with a lower bed, revealing a previously hidden vent with a broken cover. A broken vent cover was also found at Fara’s house. She explained how ‘one of the kids broke it off, then we had to put it back on with Selotape’, something which could certainly be obstructing the airflow into this room (Figure 48).

Figure 46: Pieces of furniture obstructing the wall inlets in master bedroom (left) and daughter’s bedroom (right) (Ali, Case A)

Figure 47: Wall inlet hidden behind cupboard (Karen, Case A)

Figure 48: Wall vent cover repaired with tape (Karen, Case A)

Fara’s house is exceptionally densely occupied. As there are 11 people living in a four bedroom house, the family have had to be creative with how they use the space, with the living room doubling as a master bedroom and pull-out mattresses used for the smaller children. There is little furniture in the dwelling; in particular, there were no wardrobes. Instead, clothes are hung on rails suspended from the mezzanine storage area, as well as from the living room door. It is unsurprising that damage from wear and tear occurs in a house that is so densely occupied.

The adult residents in this house use a fridge as a filing cabinet to protect important documents from one of their eight children, who has a disability. For the same reason, the thermostat has been taped over so that the settings cannot be tampered with.

The positioning of the vents in the wall, rather than the more conventional arrangement where trickle vents are located within the window frame itself, may explain why more obstructed vents were observed at these properties than at the other two cases. It would be more surprising to encounter furniture placed directly in front of windows than against the wall. However, this was actually observed in Karen’s kitchen, where additional white goods have been installed in a position that blocks access to the side window (Figure 104).

In contrast, at Case C, where trickle vents are located within the window frame, only one instance was observed where windows had been covered up, blocking the vents. The resident, Carla, had positioned the wardrobe in her bedroom in front of a large balcony window, so as to reduce the draughts which she felt were making the house cold. She believed that her strategy was effective, although she noted that ‘it’s costing me the lights’ as the room is now much darker. Carla’s house was quite full, with several pieces of furniture and other possessions in each room. For example, there is a pile of books and boxes on top of the high level kitchen units. These are stacked up right below the ceiling extract grille, which is located beside the wall, close to the corner of the room, in a way that they could potentially interfere with airflows if the pile were to get any taller (Figure 171, Appendix). A similar arrangement was observed at Sarah’s house, where a bathroom cabinet had been installed directly under the extract vent, with various toiletries placed on top of it (Figure 176, Appendix).

There are no trickle vents at Case B as air is both supplied and removed through ceiling terminals, none of which were found be obstructed at the visited flats. However, in one flat, an area of exposed ductwork in the cupboard where the fan unit is housed has been squashed by the residents’ possessions. Anthony explains how ‘we’re short of storage space. So every available nook and cranny is filled’. This includes using the AHU as a makeshift wardrobe (Figure 49). Originally the ductwork had been boxed in but this was removed at the commissioning stage and not replaced. The current arrangement of stored items competing for space with ventilation ducts risks damaging the performance of the ventilation system.

Figure 49: Fan unit ductwork squashed by residents’ possessions (Anthony, Case B)

Gaps under doors

According to ADF a 10 mm gap is required under each internal door in a dwelling to enable the passage of air between connected spaces (as discussed previously in section 2.1.5, (HM Government, 2010a)). Without this gap, the air path would be obstructed whenever internal doors are closed. At Ali’s house, the residents have laid a fitted carpet over the wooden floors in the living room. The carpet, combined with the ‘warping effect of the floor in that corner’ which has caused the floor to rise in places, means that there is now no ventilation gap under the door between the living room and hallway. The architect mentioned that this ‘deflection in the floor’

was one of the main problems that had arisen during construction:

‘As a consequence really of the builders-- well the floor construction got wet and the sheeting on the top of it wasn’t really fixed properly and then they put the finished flooring on top of that and it was all a bit-- and some of the houses, two or three of them, they took it up and redid it which made it much better.’ [Christopher]

Despite the remedial action, the problem remains in at least this one property. The combination of this deflection and the layering of a carpet over the top of it is now restricting the movement of the door, as well as partially obstructing one of the air passages required by ADF (HM Government, 2010a). This is an example of how some of the constraints and enablements of technical systems cannot always be foreseen, but rather emerge from technical practice and quickly become enmeshed into the performance of technical systems.

Four residents at Case B had also installed fitted carpets in their new apartment (Betty, Paul, Anthony, and Steve). Anthony explains how ‘we never have the doors closed’; therefore, if this is true, the movement of air between the habitable and wet spaces is unlikely to be obstructed by the carpet in this particular dwelling. On the other hand, Steve found that he was unable to close the doors in his flat after having a new carpet laid:

‘I bought my own carpets, moved in, got them laid down. Then I got a text from the people who done the carpet [….] the carpets were so thick the doors were undercutting the carpet, really cutting in [….]. Do you know what I mean? When I put the door on “krkrkrkr”, really bad’.

His brother’s friend, a carpenter, came to fix the problem by sawing off part of bottom of the door. However, he was presumably unaware of the 10 mm rule, advising that ‘I don’t want to take too much off otherwise in the winter [when] you shut your doors you get a draught’ so that now the carpets fit snuggly up to the bottom of the door, which prevents air movement out of the room when closed. The resident was upset by this experience and noted that his expensive new carpet had been damaged through the effect of the sawn door scratching against it every time it is opened or closed. Fortunately, the arrangement of ventilation inlets and outlets in this apartment means that the ventilation strategy does not rely on air passing underneath this door;

this is because both inlets and outlets are present in the open plan living and kitchen area, as well as on the other side of the door, effectively creating two separate ventilation ‘paths’ which do not cross (Figure 50).

Figure 50: Anticipated ventilation paths through flat (Steve, Case B) (1:150)

Although the extent to which these obstructions have affected ventilation at these particular dwellings is uncertain, the lack of ventilation gap is a potentially serious departure from the design intention, particularly in those dwellings, such as Ali’s house, where the ventilation strategy anticipates the free movement of air into and through the living room, to the kitchen, where stale air is finally extracted (Figure 51). Furthermore, issues may arise when the residents change, as the new tenants may not leave doors open all the time and could end up suffering the effects of poor ventilation.

Figure 51: Plan showing how the ventilation design could be compromised by poorly installed floor combined with resident’s modifications to building fabric (1:150)