First of all we need to understand the energy consumption by user and period of time. From here we can easily see that we really use a lot of energy just to heat our homes. Did you ever wonder how much kWh/m2a  does your house consume?   Energy consumption converted in money  for a average house compare with a energy efficient house and PassivHaus (Passive House) kWh/m2a is representing how much energy a house need to heat a squer meter. As a conversion, 15kWh is created by burning 1.5 liters of oil or 1.5m3 of natural gas. Just to see the main difference between today’s energy efficient building and the PassivHaus U-value (W/m2K) – The value represents the HEAT LOSS which is characteristic to each element. Basically the number represents the watts heat lost per square meter at one degree temperature difference. A higher U value = bigger the lost, A lower U value = lower heat lost. Λ (W/mK) is the thermal conductivity of each layer form the element Insulations materials work because they have trapped pockets of air which reduce the conductivity PassivHaus ( Passive House) is about perfect designing. In a PassivHaus, the 15kWh/m2a heat is supply by heated air from the hi-energy efficient mechanical ventilation heat recovery system, the rest is gain from the sun, internal appliances and peoples. Basically, all the heat loss from the walls, roof, windows, foundation and ventilation is compensated by  heat gain from the sun, home electronics, humans and maximum 15kWh/m2a hated air. The below figure is a print screen from the PHPP (Passive House Planning Package) which show exactly in kWh/m2a how much is lost and gain in a typical PassivHaus.   When we are speaking about energy  regarding to any PassivHaus we only need to remember 3 numbers. One is the limit for heat demand, one for heat power and the other for the primary energy 15kWh/m2a of heating energy can be deliver by heated air, at a maximum temperature of 55C. The 120kWh/m2a includes the heating energy demand, domestic heated water and the total buildigns appliances. Generally, 30-40kWh/m2a is the heating + domestic heated water, the rest 80-90 kWh/m2a remains for the appliances. “PassivHaus (Passive House) buildings are very well insulated, draught-proofed buildings whose annual space heating is so low that the conventional heating system can be omitted. The small amount of heat still can be delivered to the individual rooms by heating the air supplied by the ventilation system.” – PHPP To obtain a PassivHaus (Passive House), both designing and the constructing process few principles needed to be strictly follow. The U value  is generally depending on the position, climate and the size of the building. The air tightness value it is ONLY determine by the door blower test at a pressure and depressor of 50PA. The window is the weakest link for the house, It’s required a very special attention. Attention!!! The U value it’s refer to the total window, after the instalment, not only for the glass. As I previously mention, PassivHaus is about details. Thermal bridges may appear at all elements intersections, or penetration.   The Mecahnical ventilation with heat recovery system (MVHR) is one of the important peace of equipment from the house. It’s provide fresh air in all the rooms, creating the perfect climate, humidity and ambience in the building. The high efficient system, recovers up to 95% – 97% of heat from the house. Practically, the heat from the used air is passed throw the new air, without any air contact. Attention!! The MVHR it always used fresh air, it only recover the heat form the used air. The best part from all is that all kinds of buildgins, egther new or old can be design to PassivHaus standards. ZecaPH purpose is to find the best solution for