Passive Houses

_ _ _ _

What do we call an energy-efficient building?

 

The amount of energy used for the heating and cooling of energy-efficient, low-energy houses is much lower than the energy used in buildings built according to the present energy prescriptions.

 

However, specialists disagree on how much lower the energy use should be. Certain engineers treat a building as being a low-energy building if its annual energy demand is under 60-70 kWh/m2, but we draw the line at about a value of 20-30 kWh/m² per year.

 

In comparison, in the case of a Hungarian residential building built in the 2000s, this figure is 90-100 kWh/m2 per year, and the average for obsolete Hungarian homes is 220 kWh/m2 per year.

 

The passive house concept

 

A passive house is an energy-efficient building in which a pleasant interior temperature is ensured in an exceptionally energy efficient way using passive architectural and building engineering solutions:

    • suitably oriented, compact building
    • optimally heat-insulated building shell free of thermal bridges
    • air-tight delimiting structures
    • solar energy utilisation with large, south-oriented PH doors and windows
    • highly efficient heat-recirculating ventilation
    • passive protection against overheating in summer

In order for the set objective, i.e. a maximum of 15 kWh/m² per year

 

Only those buildings may be called passive houses that comply with the attestation criteria of the PHI and that have been granted the “Certified Passive House” certificate as a result of their quality control process.

 

What is a well-designed passive house like?

 

The secret of the passive house concept is not in special construction systems, building structures or in the use of special building engineering equipment. Passive house quality can be achieved with the application of building materials and elements used today in accordance with the PH requirement system, with the utilisation of solar radiation and internal heat gains (the heat generated by the residents and the household equipment), with careful architectural and building engineering planning and construction.

 

In a well-designed passive house:

    • a high degree of comfort is ensured for the residents
    • the temperature of the internal surfaces is even
    • there are no draughts
    • there is no internal condensation or mould
    • the air is always fresh and free of pollen
    • the heating and cooling costs are low

 

High architectural and engineering quality is guaranteed by the fact that planning is carried out by our qualified passive house planning staff and subcontractors listed in the Passive House Institute’s international database.

 

The passive house requirement system

 

It is the planner that first checks compliance with the certification criteria during the planning process with the help of an MS Excel-based programme developed by the Passive House Institute. Then, the certifier checks this during the certification procedure. We are in possession of a user licence of the Hungarian language version of the programme, the Passive House Planning Package (PHPP).

 

In order to acquire the certification, using the PHPP for calculations, the following conditions must be certified in the case of a passive family home:

    • annual heating and/or cooling heating demand: max. 15 kWh/m2 per year,
    • or heating load: max 10 W/m2
    • the building’s total primary energy demand: max. 120 kWh/m2 per year
    • air-tightness max. 0.6 1/h (data measured at a pressure difference of 50 Pa)
    • the frequency of overheating (internal temperature over 25 °C) should be under 10% at an annual level

 

Slightly different certification conditions apply to building renovation with a passive house approach and to non-residential function passive buildings.

 

In the interest of fulfilling the conditions, there are separate prescriptions that apply to certain installed structures and engineering systems:

    • heat emission of the external solid delimiting structures (walls, floors): U ≤ 0.15 W/m2K
    • heat emission of façade doors and windows: Uw ≤ 0.80 W/m2K
    • heat recovery efficiency of ventilation equipment min. 75%

 

Contrary to popular belief, it is not compulsory to provide the building’s heating and hot water supply from geothermal energy sources. The heating energy demand of passive houses is very low, therefore the heat supply may be economically ensured from traditional energy carriers, e.g. with gas or pellet-fired heating as well. An important aspect is that in this case the cost price of the heating system is much lower than that of a solar or geothermal system.

 

Passive house planning and technical supervision

 

The planning process is not fundamentally different to that of a non-passive house, but in the interest of an optimal result, developers must already know whether they are going to build a passive house or not when selecting the plot. The subsequent re-planning of finished concept plans or of buildings that already have a construction permit is only possible to the detriment of cost-efficiency and the latter task cannot even be carried out in most cases without a permit amendment.

In the knowledge of the meteorological data relating to the location, the building must be planned by continuously controlling the energy gains and losses.

When creating the concept and all the way through the entire planning process, the plans must be checked and re-checked after every step using the PHPP programme.

We provide assistance to the developer during the entire planning and construction process, starting with the selection of the plot or the preliminary cost estimate all the way to the acquisition of the PH certificate:

– General planning

    • consulting before selecting the plot
    • drawing up the concept plan, selection of the structural systems
    • 3D visualisation plans, computer model
    • creating the energy concept, planning renewable energy sources
    • energy-related consulting in case of refurbishment of existing buildings in passive house quality or with an energy-efficient approach
    • drawing up the Building Permit Plan, collaboration in the permit procedures
    • drawing up Construction Plans, with specialist plans, junction solutions, with PHPP calculation
    • drawing up the as-built documentation

 

Investment consulting and technical supervision

    • decision preparation, cost estimation, economy calculations
    • continuous cost control during the planning and construction phases
    • preparation of calls for tender, contractors’ competitive bidding
    • technical supervision per specialist field
    • checking and approval of performance by general contractor
    • carrying out the technical completion procedure
    • collaboration in obtaining the occupancy permit

 

Collaboration in the PH certification process

    • collaboration in the certification process
    • putting together the documentation required for the preliminary certification of the plans
    • tracking changes during construction, continuous updating of the PHPP calculation

 

Near zero energy buildings

 

The objective of the European Directive 2010/31/EU on the energy performance of buildings was to increase the number of near zero energy buildings. From 1 January 2021, only near zero energy buildings may be built in EU Member States. The energy demand of these buildings must be reduced to a minimum, on an annual basis 25% of the energy used must be produced in the building or in its environment.

Although passive houses and near zero energy buildings are not the same, it can be said that passive residential buildings with a renewable energy supply can achieve this objective in the most cost-effective way.

Building a passive house represents an approximate extra cost of 15-20% ompared to buildings that comply with the present building energy prescriptions. In spite of this, in this transitional period it is not worth creating a building with a 50-year lifespan that becomes almost immediately obsolete at the moment it is completed.

 

Is an active house an energy-efficient building?

 

Not essentially. In the case of active houses, contrary to passive houses, it is not the building’s energy requirement that is reduced to a minimum; instead, the building’s heating and other energy demands are covered and exceeded by installing active energy production elements. Unfortunately, the very high cost price and relatively short, 15-20 year lifespan of the currently available active elements (e.g. solar cells) means that the investment is not returned.

 

Planning green buildings

 

Environmentally conscious, A green buildings are low energy demand buildings that have a minimised environmental burden during their entire lifecycle – from creation, through operation and renovation, all the way to demolition. Recyclable construction materials produced in the vicinity of the construction location are used in an environmentally friendly way for the construction of such buildings, and the construction is an energy-efficient process that involves low environmental pollution and a small amount of waste production.

The planning of environmentally friendly and energy-efficient building structures is a complex task and requires a great amount of care and attention, not just from the general planner architect but from all of the engineer specialists as well.

Green buildings must be operated in an energy-efficient way by using renewable energy sources. Electrical energy is usually produced within the plot with solar cells and the heating and cooling heat energy may be ensured from solar or geothermal solutions. To date, we have mainly had experience with the planning of solar and ground probe systems, but we have also examined the installation possibilities of soil collector and well systems.

Another important issue is the treatment of the waste, wastewater and precipitation water created in the building. By collecting precipitation water, it may be used for watering and, along with biologically treated wastewater, as “grey water” for cleaning, washing and for WC flushing.

 

Green classification systems

There are several foreign environmental protection classification systems in existence, and these have appeared on the Hungarian market as well with office and commercial buildings receiving certification in recent years. Almost all newly constructed, A-category office buildings have some sort of certification, which serves as a guarantee for the developer or tenant desiring the certification that the building developed or leased by it was built in an environmentally conscious way and operates sustainably. Such classification systems include the British BREEAM és LEED, the German DGNB and the EU Green Building.