Modern natural ventilation in residential construction

Modern natural ventilation in residential construction – In residential buildings, mass housing traditionally performed natural ventilation . However , the stability of its work depends on many factors , whose effects are often negatively affects the quality of indoor air . It should be noted that it is not always maintained the requirement for vents in the narrow leaf , or swing-out mechanism in the narrow leaf , or, if necessary , soundproofing valve. Low quality sealing intercommunication building openings and joints , as well as leaks doors in the apartment reduce the effectiveness of the ventilation by 15-30% . Leaks in blocks vents , clogging them make the hood in some cases even unworkable.

If poorly designed exhaust ventilation , or clogged, or illegally reconstructed , the situation with regard to the required air becomes almost hopeless. Mold lesions on the walls, high humidity caused by smokers but increased tightness of windows, by the fact that in the new environment construction organizations build and rent houses in a short time , and the tenants occupy the apartment in which a year or two “wet” wall . To create a standard climate of apartments require intensive airing of premises , and sometimes drying walls. Design decisions at the expense of public airing vents , transoms , or rotary flaps significantly reduce the thermal efficiency of window designs and comfort of living .

The use of synthetic surfacing materials in buildings , distribution of dust mites in the apartments also lead to a reduction of indoor air quality and increase the ventilation requirements . Larger dust outside atmosphere calls for air supply .

The disadvantages of natural ventilation should include the fact that it is difficult to reconcile with the modern demands of energy conservation. When installing thermostats on heating devices , there is a real opportunity to save heat in the heating system . Thus , 30 to 75 % of installed thermal power of the system is the need to heat for heating the ventilation air . Energy conservation would be more effective if ventilation could work with VAV . Organizing such a regulation under natural ventilation is virtually impossible.

Ventilation system with mechanical drive

Equipment supply systems of residential buildings ventilation occurs much less frequently than mechanical exhaust as it significantly increases the cost of the project due to the cost of the system , space for supply installation and space required for installation ducts. The advantage of mechanical air supply systems is guaranteed supply design flow of supply air to each apartment , the ability to provide fresh air and reduce allergic diseases , the possibility of air distribution , exclusive blast regardless of the weather outside, the possibility of saving energy through heat recovery of exhaust air to heat supply . The disadvantages besides expensive , should be attributed the deterioration of the ion composition of the air space, the cost of electricity to move the supply air , possible additional heat loss in the plenum and ducts.

Usually set at least two air supply systems of the building . If possible, the air intake of the green zone , plenum chamber located in the basement. If the bottom of the clean air is not possible to pick up , it is set on the upper technical floor .

Ventilation ducts metal – trunks with ” satellites ” – located in the technical mines inside the apartment , of which the following distribution of the supply air directly into the room. At the same time , distributing air intakes provided for false ceiling partition wall of the hall. In tall buildings on each zone height of 10-12 floors are designed independent trunks air intakes . Winter supply air is heated to a temperature of 20 ° C, in summer – outdoor . In addition, the plenum chamber air is filtered in a dry filter type 5 EU , EU 6. Air supply system selected on the basis of disposable pressure required for ventilation network connection inside apartment .

Application of mechanical air supply system requires, as a rule , the use of mechanical ventilation and a roof fan . The presence of mechanical supply and exhaust system makes it possible to dispose of the exhaust air heat . Application ventilation system with a recuperative heat exchanger plate in the middle of Russia in the most cold peaks requires preheat supply air to avoid freezing of condensate in the exhaust air path . Known circuit with door-to-door supply and exhaust systems and heat recovery , where preheating influx done individually . There is a positive experience with such systems in low-rise buildings .

Exhaust ventilation system with mechanical drive

During mechanical ventilation , and especially with supply limiting valves air throughput , should pay attention to the density of room doors . Large doors breathability creates a problem overflowing the exhaust air of the apartments on the lower floors of the stairwell to the upper floors of apartments , with the result that , even in a well-functioning ventilation , fresh air is greatly reduced. In buildings with one-sided arrangement of apartments , this problem is compounded by the possibility of horizontal spillover of the apartments on the windward side to the leeward facade apartment .

SNIP ” Construction Firing ” imposes on apartment doors requirement of high integrity, providing breathability no more than 1.5 kg / ( m2 • h ), which should virtually cut off from the apartment stairs and elevator shaft . Under actual conditions this requirement is generally not fulfilled. Where natural ventilation rate density doors could be even lower . When mechanical ventilation in the apartments are large vacuum and suction through leaky doors can not be excluded .

Decentralized system of door-to-door ventilation

Trying to avoid the disadvantages of centralized supply and exhaust ventilation systems led to the development of decentralized door-to-door supply and exhaust system with heat recovery . This system has the following advantages:

permanent ventilation of all habitable space ;

relative air humidity does not exceed 45 % ;
thanks twice filtering ensured supply of clean air ;
savings due to heat recovery up to 20 %.
So-called system «System Airaterm» allows to smoothly adjust ventilation , taking into account solar radiation and wind speed , reaching a thermal efficiency of 66-80 % , and providing indoor humidity level of 45-55 %. When you receive air flow 34 m3 / h , the noise level is 21 dB ( almost inaudible ) . At a flow rate of 60 m3 / h noise level – 32 dB (quiet rustling of leaves ), and at a rate of 80 m3 / h – 39 dBA (noise computer fan ) . Such a system with recycling are already operating successfully in Germany in five-and ten-story buildings.

Ventilation system with heat recovery (Erfurt )

The basic principle is that the first set for each apartment unit air vent with integrated heat exchanger. This means that each apartment gets its ” ventilation equipment .” Along with the installation of ventilation , it is necessary to ensure fast approach of supply and exhaust air removal . Serve this purpose separate vertical shafts that run through all the residential floors . Large-sized parts of the system ( device ventilation shaft inlet air supply and exhaust air ) are located in a mine health , between the kitchen and bathroom. In addition to high-efficiency heat exchanger , air handling unit is equipped with a so-called boxing fan , heat exchanger through which the exhaust air is absorbed and passed the inlet air pressure on the countercurrent principle . When you close passage reverse flow air distribution by small channels , supply air robs exhaust air up to 93% of heat ( efficiency ) .

An integral part of the venting device are the internal filters which , in order to protect the heat exchanger  filtered and exhaust air . Exhaust air through valves premises sucked into the kitchen and bathroom, which , in turn, are equipped with additional filters. After passing through the heat exchanger , the exhaust air is led into the central shaft, through which the roof outputs it outside.

Since the intake air before passage through the ventilating device is also passed through the filter into the outer shaft central air supply , it is obvious that this air stream is filtered twice . ” Heated ” fresh air on a flat ( pans ) channels is distributed mainly in the lobby and at the so-called long- ejection nozzles is injected into each room of the apartment. In the lobby of the required air distribution channels have flat or “cached ” suspended ceiling. Depending on the location of the heat exchanger in the mine requires JavaScript lookout doors in the bathroom or in the lobby.

Comparison with other technologies , which provide measures to reduce emission of CO2, shows that the ” heat recovery ” in relation to solar thermal installations , photovoltaic ( photovoltaic ) installations can be seen as a much more economical. The ratio between the energy savings and investment costs in air vent with a decentralized (relating to the apartment) heat recovery is 6-10 times more favorable relevant parameters in the above-mentioned technologies.

The problems of waste disposal , using existing photovoltaic (heavy metals such as cadmium, lead, etc. ) , do not occur after the expiration of the service units with heat recovery . When outdoor temperatures from -10,5 ° C only due to the effect of regeneration air warmed this waste heat to a temperature of 17,1 ° C. The temperature of the exhaust air temperature was 19,0 ° C. Analysis of accumulated recently evidence indicates heat overrun of about 25 % at the site without having to install a heat recovery .

The need to improve standards for the design of ventilation systems

Compare our standards with the norms of the German air shows that for small apartments our standards more stringent , as the lower boundary of air they do not fall below 110-140 m3 / h At the same time, according to German standards flats 50 m2 of total area required air flow of 60 m3 / h, and in the flats 50-80 m2 – 90 m3 / h Some experts suggest to consider the base rate of inflow and extraction rate – peak . Then the Russian and German standards will be closer . However , this proposal is only possible at a controlled ventilation, which as mentioned above , it is easier to implement when the mechanical system .