In passive wooden houses, the need for heating and cooling can be met with very little energy input, however, because of this, it is important that a smart strategy be put in place to achieve the goal with minimal effort while avoiding waste.
The leaky case
Passive wooden houses are designed to be airtight so that there is no draft.
It is quite obvious that a drafty house is impossible to heatand that it is an energy sieve. That’s why the houses we make today are drafty.
The air exchange
Drafts performed an important function in the house of the past: reciprocating air.
Air exchange was also performed regularly in the morning when one got up, made the beds and opened the windows wide. These are somewhat obsolete activities today with comforters and sheets always stretched taut and the daily action of making the bed takes much less time. They also do not open the windows wide regularly because the occupants often work.
That is why air exchange is as important as thesupply of thermal energyto the house.
In summer instead of contributing thermal energy, it will instead be necessary to subtract energy, and this is what is done with summer air conditioning.
Air exchange will still be necessary, and it is also a good idea to provide for air dehumidification, thus greatly improving comfort in the summer period. This air exchange is achieved with centralized mechanical ventilation VMC.
One of Europe’s leading companies in central ventilation with heat recovery is Zhender, a very reliable Swiss company. Their site offers a lot of useful information: Product overview – comfort ventilation for living spaces | Zehnder Group Italia S.r.l.
Methods for heating or cooling
Heating and air conditioning today is done with heat pumps. The traditional gas boiler, even in its more advanced version with condensing heat recovery remains polluting as it emits CO2 into the atmosphere.
A heat pump is a boiler that not only generates heat but also removes it by cooling rooms in the summertime.
There are two ways to heat or cool:
- hydronic system
- aeraulic system
In wooden houses, both are used, and much depends on the sensitivity and expectations of the users.
The hydronic system
The hydronic system involves heating or cooling water by means of a heat pump, and the heat transferred to the water will then be transmitted to the room by radiant panels equipped with water-filled pipes.
This is the most traditional system in the sense that radiant floors, for example, have now been widely used for at least 30 years.
The system involves water brought in with a hydronic heat pump at a temperature of about 30 degrees-stored in a small inertial tank-being flowed into panels that can be placed on the floor, wall or ceiling.
The advantage of this system is that the heat is radiative, thus allowing it to ensure excellent well-being without overheating the air but warming the body with a radiative effect.
In addition, the same heat pump that heats pipe water is also capable of heating domestic water.
The hydronic system plans to work in conjunction with a VMC system especially in the summer period in which the VMC will need to provide air dehumidification.
The aeraulic system
These are the systems that transfer the required heat to the environment by heating or cooling the air. Air systems that supplement mechanical ventilation with a more substantial supply of treated air belong to this type.
These types of systems are becoming increasingly popular in wooden houses.
Perhaps the reason for the success of these systems is their ease of use. A single system with a single control system makes it very easy to program and manage the temperature even remotely.
Some firms such as Mylar https://it.mydatec.com/ call it Thermodynamic Mechanical Ventilation, others such as Irsap call it Adaptive Climate Ventilation https://www.irsap.com/it/ventilazione-meccanica-controllata/climatizzazione however, it is always a ventilation system enhanced by a heat pump. Nle case of Irsap the heat pump is external to the package and can be replaced or integrated freely.
Compact aggregate plants
Still on the subject of aeraulics I think it is worth mentioning a very compact machine that in a small space performs ventilation, heating, air conditioning and domestic hot water generation. It is manufactured by the company Brofer of Treviso https://www.brofer.it/focus.asp
This is a machine designed for passive houses. The power is limited because it is designed for well-insulated rooms without large leakage.
The size is that of a household refrigerator but in a small space it condenses the functions of a true central heating unit.
Conclusions
Electric systems for providing heat pump energy are reliable and have achieved very high levels of efficiency. We can therefore safely put systems that used fossil fuels to heat our homes into oblivion.
The professor who taught me technical physics at the University of Padua in the 1980s was a proponent of the advantages of radiant panel heating to counteract cold wall emissions. Today, however, our houses do not have cold concrete walls but well-insulated plasterboard panels with several inches of insulating fibers.
Therefore, the boundary conditions have changed a lot, and since air ducts have to be made to ventilate rooms anyway, it is not wrong to think of focusing everything on ventilation to ensure living comfort.