Environmental product declarations provide quantified environmental data of products using predetermined parameters and, where relevant, additional environmental information. For environmental declarations on building products the standards ISO 14025 (Type III environmental declarations) and ISO 21930 (Environmental declaration of building products) apply.
For the study at hand three central propositions of the ISO-framework are of particular interest:
1. Communication format
2. Comparability of building products
3. Life cycle assessment for building products
The objective of the study is to define a model house which can be used in EPDs of building products. Main target group is the end-consumer, therefore detached single-family-houses are considered. The model house could be used for different applications in environmental declarations of building products, for example:
- Calculating the energy savings due to thermal insulation
- Modelling the emissions of interior materials as wall paints or floor coverings to indoor air
Estimating the release of metals from zinc or copper covering due to precipitable water
The following steps were taken to develop the model house:
- Basic considerations concerning environmental performance of buildings
- Research work on European housing characteristics
- Suggestion for a model house for the moderate climate zone
- Examples how this model house could be used in Type III environmental declarations (EPD).
In the study we want to experiment with the idea of a model house and show with some crucial examples whether it can help to facilitate the creation and comprehensibility of scenarios in EPD. Consequently we do not concentrate on the perfectly defined and widely accepted model house. The main findings for the definitions of the model house are:
- In principle the model house should be applicable throughout the EU-25 countries. In order to simplify the spread of European climate conditions we devided the EU-25 members in three climate zones: cold, moderate, hot. In view of the project budget we had to limit our efforts to a suitable model for the moderate climate zone.
- Because of missing accordance between the calculation methods for statistical and regional climate data we use the German standard climate (corresponding to Cologne) of our calculation tool [PHPP] as our reference (30 % of private households, heating degree days similar to average value of moderate climate zone).
- The number of rooms is set to 4 according to [Housing Statistics 2004]. The kitchen is not counted as separate room.
- The number of occupants is set to 2.5 and corresponds to the average number of persons per occupied dwelling according to [Housing Statistics 2004]
- ince no statistical data for average useable floor areas of buildings are available we adopt the useable floor area and the number of storeys from [Ecofys 2004]. The mean ceiling height is set to 2.80 m.
- In future, energy saving and landscape protection will become even more important than nowadays. Presumably, the detached single-family house is going to survive in the next years but it will have to meet stronger requirements. The more compact a building is the better it can meet these requirements. Therefore we assume that the form of the model house approaches a cubus leading to a form factor of 0.72.
- Based on the above formulated presumption concerning the compactness of the building the roof is constructed as a pent roof, the attic forms the second storey. Under the maxime that open space shall be maximised outbuildings are ignored and a cellar is used as storage space (unheated).
- Transmission heat loss -
- Since the EPBD does not give minimum levels for energy performance or thermal insulation, interviews with building authorities and experts throughout Europe that were carried out in [Ecofys 2004] were intended to deliver European U-values. As the comparison with the actual minimum requirements in Austria shows some countries undercut these estimated future Uvalues already now. In default of other European data we took the minimum required U-values in Austria.
- Thermal bridges were set to 10 % of transmission loss.
- Ventilation heat loss:
- Since market penetration of mechanical ventilation is still low for residential buildings in EU-25 countries with moderate climate we assume only natural ventilation. The air change rate of the building is set to the value of 0.5 according to EN 832 for natural ventilated single-familyhouses with high air tightness.
- Solar and internal heat gains:
- Only direct passive solar energy gains are considered. The design of building provides orientation to the south and thermal zoning. -The heat storage capacity of the building materials is neglected for the calculation of the heat demand.
- [PHPP] proposes 2.1 W/m2 as a standard value for the internal heat gains of residential houses.
- • Heat demand
- The heating energy demand of the model house is calculated with the tool PHPP – Passivhaus-Projektierungspaket [PHPP] which complies with the requirements of EN 832. The indoor temperature is kept on the standard value of 20 °C.
- The energy mix for heating is set according to IEA for all EU-25 countries. The efficiency rating is derived from different sources.
- The water heat demand is set to 12.5 kWh/(m2a) (according to ENEV
- German EnergieeinsparVO and DIN V-4701-10). -Hot water is not considered because of the high dependancy on user behaviour.
- Other issues
- Building materials and their influence on the model house as our central objects of investigation have no influence on water heat demand. Therefore it is not considered in the moment.
- The cooling demand for residental buildings in the moderate climate zone can easily be avoided by efficient shading systems, lowered internal gains and an adaptive ventilation strategy [Ecofys 2004]. Thus no cooling demand is considered for the moderate climate zone.
- Electricity consumption exept for heating and hot water supply is not dependent on the building properties and therefore not considered.
- Construction and deconstruction waste is part of the environmental declaration of building products. Household waste is not dependent on the building properties and therefore not considered.
- According to [Housing Statistics 2004] the average design life of single-family houses in Europe-25 ist 49 years. This is rounded to 50 years for the design life of the model house. The time period under consideration is also set to 50 years. The service life time of building materials is appointed according to [BTK 2007].
The model house is applied to an expample EPD for the following building products respectively:
- insulation material
- wall paint
- floor covering