Current house concepts
The first to appear were houses equipped with photovoltaic panels, followed by the low energy houses (typically 25-50% below the minimum requirements of the times),
and then the so-called “3-liter houses” or zero-energy/ zero-emissions homes.
Although the definitions of energy-efficient homes vary from country to country, and the concepts have not converged to a single model,
there are some particular trends, more prominent in the last 10-20 years.
Passive House (Passivhaus)
(Very low energy consumption house)
The exact definition given by the Passivhaus Institute from Germany is very technical and refers to a set of nine thermal and energy parameters of the building, with strict limits on variation. Most often it is described through “heating requirements below 15 kWh per sqm per year”.
The most important characteristics of passive houses are:
- Nearly perfect insulation of the building: no leaks, no thermal bridges, “low u – values” windows
- Use of controlled mechanical ventilation for air refreshing
- All house equipment (heat & circulation pumps, water heaters, refrigerators, etc.) are energy efficient and low consumption
- Energy is based on heat pump and passive solar energy (both heat/light and shadow through house orientation and building accessories)
This type of house is especially seen in Nordic countries.
The main drawback of this concept is the strict thermal insulation (materials, manufacturing technologies), which limits the technical feasibility of the house and drastically increases costs.
source: www.hhs-architekten.de (Manfred Hegger)
Plus Energy House
This type of house has its own sources of renewable energy which exceed its energy consumption. It has the same kind of technical requirements as the passive house, but they are less strict. The biggest challenge is the heat storage and recovery for the winter use. In the vast majority, such houses use heat pumps, which have quite prohibitive cost disadvantage (for Romania, at least).
Endorsed by the “Active House Alliance”, the Active House is an integrated, energy efficient building concept that creates a healthier and more comfortable climate, while being environment friendly.
An Active House is based on the interaction between comfort, energy efficiency and impact on the environment.
1. Comfort – it creates a comfortable and healthy indoor climate by providing and controlling daylight, temperature, fresh air
2. Energy efficiency – an Active House is energy efficient. All energy is supplied by renewable energy sources integrated in the building or from the nearby collective energy system and electricity grid
3. Environment – it has a positive impact on the environment through optimal use of resources (such as water, etc.) and by integrating into the local culture and design
Active houses are well known for their sophisticated technologies for light and ventilation control, associated with inevitable high costs. In fact, these houses were built as a pilot for research and were not (yet) developed for commercial purposes.