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 Building in accordance with the new Energy Conservation Ordinance In the rationale for the 3rd Heat Insulation Ordinance, the Federal Government declared that the next stage of the lower energy house standard would be established by the year 2000. In its development of the 1995 Heat Insulation Ordinance, the Bundesrat (German parliament) also demanded a subsequent amendment which would reduce energy consumption in new buildings by around a further 30%. Attempting to achieve this goal with structural measures alone would be the wrong technical approach. The inclusion of the heating system in the energy balance thus becomes an essential step. While in the past, demands have been made on the net energy, in future the gross energy, i.e. the end energy will be assessed, in order to include the efficiency of the system technology. However, referring the requirements to the end energy alone means that no unjustified advantages can arise for individual heat supply methods whose transformation losses occur outside the building. In order to take account of different preliminary chains in energy transformation and in the transportation of the respective energy carrier, the annual heating energy requirement must also be assessed as primary energy. The ordinance is therefore designed in such a way that the annual primary energy requirement must be proved, with obligatory demonstration of the end energy requirement (information for the consumer within the framework of the energy pass). The definition of the annual heating energy
requirement in the Energy Conservation Ordinance corresponds to a capacity
level pre-set by principle document no. 6, Energy conservation and heat
insulation, within different energy conservation methods.
Fig. 7.2.1 Energy price trend and environmental protection reinforce the trend towards low energy buildings
For technical implementation, a directive applicable throughout Europe has been created with European standard DIN EN 832 Calculation of the heating energy requirement of buildings, which can be used as a standard method for calculating the heating and heating energy requirement. German standard DIN V 4108-6 Calculation of the annual heating and annual heating energy requirement of buildings, serves to implement the European standard by defining boundary conditions which are typical for Germany. DIN V 4108-6 offers two analysis methods: For smaller buildings, the so-called heating period balance and alternatively, the more accurate monthly balance. DIN V 4107-10 Characteristic values for heating systems, with simplified graphic methods or accurate calculation methods, is provided for assessing the efficiency of heating systems.
However, the previous requirements cannot be
directly compared with the new regulations, as the transmission heat losses
are now referred to the heat-transferring encompassing area and no longer
to the heated building volume.
With regard to structural thermal bridges, the new ordinance prescribes for the first time that the thermal bridge influence must be kept as small as possible and the remaining influence taken into account. Once again, there are all-inclusive and more accurate methods for this, in which the all-inclusive estimate relating to the entire heat-transferring encompassing area of the building lies on the safe side. Thermal bridges must be taken into account in one of the following ways, when determining the annual heating requirement:
The last-mentioned method can result in the
most favourable thermal bridge losses for external components in sandwich
construction, with their connection and fastening details.
Fig. 7.2.2a Infrared photograph in the connecting area of two different sandwich profiles without thermal bridges
FFig. 7.2.2b Infrared photograph in the corner area of a wall in sandwich construction - once again, no thermal bridges are visible
Fig. 7.2.3a Infrared photograph in the internal area of a building in solid construction clearly shows thermal bridges
Fig. 7.2.3b Infrared photograph in the external area of a building in solid construction with large thermal bridges in the façade Image source Fig. 7.2.2a to 7.2.3b: Koschade, R.: Sandwich Panel Construction; Ernst & Sohn, Berlin 2002; p.42. Atmospheric density Another new inclusion in the Energy Conservation Ordinance is the possible approach based on varying levels of ventilation heat losses in buildings with normal internal temperature. Most recent experiences show an air exchange of n = 0.7 as standard value, without testing the air-tightness of the building. This can be reduced to n = 0.6, if the air-tightness of the building is checked with the standardised Blower Door method.
As in the previous Heat Insulation Ordinance, in addition to the requirements on the building as a whole, component-related additional requirements must also be made, in order to ensure minimum structural requirements at energy-critical points. These regulations occur in DIN 4108-2 with special consideration of thermal bridges and condensate formation on inner surfaces.
The Change to existing buildings is essentially an update of the Heat Insulation Ordinance with requirements on the heat transfer coefficients of external components. The instrument of conditional requirements was adapted to the latest state-of-the-art and economic viability, and the applicability thus extended. The requirements were slightly increased.
For the first time, there will also be requirements on summer heat insulation. The energy input must be limited through structural measures in such a way as to ensure sensible room air conditions in the warm season, without cooling. If excessively high room temperatures occur, then the specific cooling capacity must be limited in ventilation and air conditioning systems for cooling. In buildings whose window area proportion does not exceed 30%, corresponding analysis is naturally not necessary.
The updating of the Heat Insulation Ordinance and the Heating Installation Ordinance to the Energy Conservation Ordinance provides the planner with a set of instruments with extensive design freedom. The tightening up of the requirement level is economically justifiable, with appropriate amortisation times. With modern building materials, building methods and heating techniques, the desired saving potential can easily be achieved. The calculation method provides an integrated
approach for the energy requirement of a building, and now allows a direct
comparison with the measured consumption values.
Comparison of Waermeschutz-V (Heat Insulation Ordinance) and EnEV (Energy Conservation Ordinance) analytical reports For planners of buildings with prefabricated external components in sandwich construction, the practical question first of all arises: to what extent can the panel thicknesses remain unchanged or be increased on the basis of the new requirements. The structural requirements of the Heat Insulation Ordinance 95 and the Energy Conservation Ordinance are compared for a non object-specific industrial building, consisting of a workshop and connected office section. In both cases, the workshop, with a room temperature of 16°C, is classified as a building with a low internal temperature and the office section is classified according to the requirements for buildings with normal temperatures. The data for building component areas, volumes and heat transfer coefficients is documented in test reports C1-13/95, C1-08/01 and C1-09/01 of the FIW. For the workshop, the structural requirements for fulfilling both regulations are compared in Table A. The use of thicker sandwich panels is not necessary, on the basis of the new regulations. In buildings with normal internal temperatures, the necessary heat insulation of the external components is heavily dependent on the quality of the heating technology installation, the energy carrier and the assumption of the building's air-tightness (cf. Table B). Thus, in the case of installation of a condensing boiler run on natural gas or fuel oil and accordingly optimised distribution and control, with simultaneous assumption of a building with air-tightness testing, no changes result in the structural measures in comparison with the requirements of the Heat Insulation Ordinance. On the other hand, by simply replacing the existing boiler with a low temperature boiler, an increase in the wall and roof panel thickness of 20 mm becomes necessary. This shows that the influences on the heating
energy balance as a result of improvements or deterioration are considerable
in the heating and system technology sector. The integrated approach of
the Energy Conservation Ordinance allows architects greater flexibility
and freedom of decision, while at the same time enabling better energy
design solutions.
Analytical report by the Forschungsinstituts fuer Waermeschutz e.V. Muenchen [Munich Research Institute for Heat Insulation] for certification in accordance with the Energy Conservation Ordinance for a workshop with an office section Applicant Building Project
Report no.: C1-09/01 1. Nature of the task A heat insulation calculation in accordance with the future Energy Conservation Ordinance (EnEV) is to be performed for a non-object specific industrial project, consisting of a workshop with connecting office section. An existing heat insulation analysis in accordance with Heat Insulation Ordinance 95 is taken as the starting point. The workshop, at 16°C, is to be treated
as a building with low internal temperature (12°C < 9 < 19°C),
the office section is to be calculated in accordance with the requirements
for buildings with normal temperatures. 2. Documents Heat insulation certificate in accordance with Heat Insulation Ordinance 95 of FIW Munich of 04.10.1995 for Metecno Bausysteme GmbH (at this time: DLW-Metecno GmbH), report no. C1-13/95. 3. Building data 3.1 Description of the building The workshop and office sections are covered by a shared roof. The partition between the different rooms consists of 24 cm thick brickwork. The roof and outer walls consist of sandwich panels with polyurethane high resistance foam core which are fastened to a metal structure (see Fig. 7.2.5 and 7.2.6). 3.2 Component surfaces The component surfaces are taken from the heat insulation analysis specified under point 2 and are listed under point 3.4. Workshop Office section
3.3 Heated volume and useful area Workshop The heated gross volume is Ve = 13.715 m³. Office section The heated gross volume is Ve = 2.312 m³. The heated useful area is calculated at AN = 739,8 m². The A/Ve ratio is 1.152,0 m² / 2.312 m³ = 0,498 m-1.
Fig. 7.2.5 Annex 1 for test report C1-09/01 - Roof top view of workshop with offices and social area
Fig. 7.2.6 Annex 2 for test report C1-09/01 - Views of workshop with offices and social area 3.4 Component characteristic values Workshop: The heat transfer coefficients U of the heat-transferring enveloping surface and the total energy transmittance of the outer windows are taken from the heat insulation analysis specified under 2. Office section: The heat transfer coefficient of the windows from the heat insulation analysis specified under 2 (kF = 1.6 W/(m2.K)) is increased by 0.1 W/(m2.K), in order to take account of the future modified calculation method for windows, i.e. Uw - 1.7 W/(m2.K). The heat transfer coefficients U of the remaining
components, also of wall and roof, as well as the total energy transmittance
of the outer windows are taken from the specified heat insulation certificate. Comment The heat transfer coefficients Uw of the windows corresponds to the measurement value Uw, Bw, as determined in accordance with DIN V 4108-4 valid from the beginning of 2002, see draft standard for DIN V 4108-4 of 01.11.2001. The component characteristic values for the
workshop and the office section are listed in the two following tables
(Fig. 7.2.8 and 7.2.9).
Fig. 7.2.7 PUR sandwich panels for walls
Fig. 7.2.8 Table: Component characteristic values for workshop
Fig. 7.2.9 Table: Component characteristic values for office section
4.1 Heating installation system Condensing boiler without water heating; maximum flow/return temperature 35/28°C; installation of heating boiler outside the thermal envelope; horizontal and vertical distribution within the thermal envelope; regulated pump (heating); radiators with thermostat valve; energy carrier natural gas or liquid gas or EL fuel oil. The heating installation system only needs
to be taken into consideration for the office section. The available heat
requirement for drinking water and service water heating is set at Qw
= 0 kWh/m2a, in accordance with the regulations of the Energy Conservation
Ordinance for non-residential buildings. A printout of the heating installation
data can be found in Annex 3.
Workshop:
Office section:
Fig. 7.2.11 Joining of PUR sandwich panels for roofs
Fig. 7.2.10 PUR sandwich panels for roofs 5. Calculation Office section
6. Sunmer heat insulation
In the present example of the office section, the window area proportion is f = 0.074 and no analysis of the summer heat insulation is necessary. No analysis of the summer heat insulation is required for the workshop either.
The requirement of the Energy Conservation
Ordinance in accordance with Appendix 1 Table 1 of the Energy Conservation
Ordinance (as at 13.07.2001) is fulfilled.
The existing, specific transmission heat loss H1T,exist, relating to the enveloping surface, at 0.50 W/(m2.K) is clearly below the permissible maximum value H1T,max of 0.60 W/(m2.K). The requirement of the Energy Conservation
Ordinance in accordance with Appendix 1 Table 1 of the Energy Conservation
Ordinance (as at 13.07.2001) is fulfilled.
Gräfelfing 13.11.2001 / MS-us
Fig.7.2.12 Annex 3 to test report C1-09/01 - GALILEO - Office section
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