1. Indoor Environmental Criteria for Design and Calculation of Energy Performance of Buildings – EN15251
Bjarne W. Olesen
International Centre for Indoor Environment and Energy Technical University of Denmark
This presentation will explain the content of the standard

2. Outline The EU CENSE project Scope of the Standard Design Criteria
Energy calculations
Long term indicators
Measurements
Classification
Annexes
This is the outline of the presentation, which also includes a short description of the CENSE project

3. The EU CENSE project (Oct. 2007 - March 2010)
Aim of the project:
To accelerate adoption and improved effectiveness of the EPBD related CEN- standards in the EU Member States
These standards were successively published in the years and are being implemented or planned to be implemented in many EU Member States. However, the full implementation is not a trivial task
Main project activities:
To widely communicate role, status and content of these standards; to provide guidance on the implementation
To collect comments and good practice examples from Member States aiming to remove obstacles
To prepare recommendations to CEN for a “second generation” of standards on the integrated energy performance of buildings
The CENSE project is active since All activities are related to the EPBD-related CEN-standards, where EN15251 is one of them

4. Brief introduction
A brief introduction to the CENSE project and the CEN-EPBD standards is provided in a separate presentation:
Several documents are available from this project

5. More information More information and downloads: www.iee-cense.eu
Disclaimer:
CENSE has received funding from the Community’s Intelligent Energy Europe programme under the contract EIE/07/069/SI
The content of this presentation reflects the authors view. The author(s) and the European Commission are not liable for any use that may be made of the information contained therein.
Moreover, because this is an interim result of the project: any conclusions are only preliminary and may change in the course of the project based on further feedback from the contributors, additional collected information and/or increased insight.
Which you can easily access at the CENSE home page

6. Content of EN15251
6. DESIGN CRITERIA FOR DIMENSIONING OF BUILDINGS AND HVAC SYSTEMS
7. INDOOR ENVIRONMENT PARAMETERS FOR ENERGY CALCULATION
8. EVALUATION OF THE INDOOR ENVIRONMENT AND LONG TERM INDICATORS
9. INSPECTION AND MEASUREMENTS OF THE INDOOR ENVIRONMENT IN EXISTING BUILDINGS
10. CLASSIFICATION AND CERTIFICATION OF THE INDOOR ENVIRONMENT
The standard is divided in several sections including indoor environmental criteria for design, energy calculations, long term evaluations and recommended methods for classification.

7. Categories Explanation Category I
High level of expectation and is recommended for spaces occupied by very sensitive and fragile persons with special requirements like handicapped, sick, very young children and elderly persons II
Normal level of expectation and should be used for new buildings and renovations
III
An acceptable, moderate level of expectation and may be used for existing buildings IV
Values outside the criteria for the above categories. This category should only be accepted for a limited part of the year
The criteria for the different indoor environmental factors are given for different categories of the indoor environment.

8. Design Criteria
Design criteria for the indoor environment shall be documented by the designer.
Design criteria for the indoor environment can also be displayed along with the energy certificate
Design values for the indoor temperature for heating load and cooling load calculations shall be specified at national level.
As a default a method is recommended for establishing criteria
In general, default criteria are listed in annexes. The actual criteria have to be agreed upon on a case by case (project by project) basis or can be defined at national level.

9. Maximum for cooling (summer season), ~ 0,5 clo
Recommended categories for design of mechanical heated and cooled buildings
Type of building/ space
Cate-gory
Operative temperature oC
Minimum for heating (winter season), ~ 1,0 clo
Maximum for cooling (summer season), ~ 0,5 clo
Residential buildings: living spaces (bed rooms, drawing room, kitchen etc)
Sedentary ~ 1,2 met A
21,0
25,5 B
20,0
26,0 C
19,0
27,0
Single office (cellular office)
Landscaped office (open plan office)
Conference room
The table shows an example of design criteria for the indoor temperature for some typical spaces. It is important to notice that the design criteria are based on an assumption of different clothing levels for summer and winter. So heating systems must be dimensioned for the minimum indoor operative temperature for winter and a cooling systems for the maximum operative temperature in summer.

10. Temperature ranges for hourly calculation of cooling and heating energy in three categories of indoor environment
For calculations of energy demand for heating and cooling there is both an upper and a lower value. This means that in summer it is not acceptable to create too low temperatures e.g. by applying too much night cooling. The criteria are only valid for the time of occupancy.

11. Recommended temperature ranges for buildings without mechanical systems
For narural ventilated or free running buildings without mechanical cooling people’s expectations regarding an acceptable indoor temperature are different and depend on the longer term outdoor temperature.

12. Recommended ventilation rates for non-residential buildings for three categories
The total recommended ventilation rate is calculated as the sum of the ventilation rate required to dilute emissions from people and building according to the following equation
Where
qtot= total ventilation rate of the room, l/s
n = design value for the number of the persons in the room,-
qp = ventilation rate for occupancy per person, l/s, pers
A= room floor area, m2
qB = ventilation rate for emissions from building, l/s,m2
Internal polution sources consist of emissions from people (bioeffluents) and emissions from the building itself (furnishing, HVAC system).

13. Recommended ventilation rates for non-residential buildings for three categories
Type of building or space
Cate-gory
Floor area m2/per-son qp qB
qtot
l/s, m2
for occupancy
l/s,m2
for very low-polluted building
for low-polluted building
for non-low polluted building
Single office I 10
1,0
0,5
1,5
2,0
3,0 II
0,7
0,3
1,4
2,1
III
0,4
0,2
0,6
0,8
1,2
Land-scaped office 15
1,7
2,7
1,9
1,1
Confe-rence room 2
5,0
5,5
6,0
7,0
3,5
3,8
4,2
4,9
2,2
2,4
2,8
Class room
The ventilation rates recommended for indoor air quality should be used for energy demand calculations. The table include values for the people part and the building part as shown in the table. Also the total value is listed in the table. The buildings are divided in three types according to the type of materials used. It is also assumed that the ventilation efficiency is 1, complete mixing.

14. Ventilation for Residential Buildings
Cate-
gory
Air change rate
Living room and bedrooms, mainly outdoor air flow
Exhaust air flow, l/s
l/s,m2
(1)
ach
l/s, pers2)
(2)
l/s/m2
(3)
Kitchen
(4a)
Bathrooms
(4b)
Toilets
(4) I
0,49
0,7 10
1,4 28 20 14 II
0,42
0,6 7
1,0 15
III
0,35
0,5 4
Similar recommended values for residential buildings

15. Deviations
The different parameters for the indoor environment of the building meets the criteria of a specified category when:
The parameter in the rooms representing 95% of the occupied space is not more than 3% (or 5%) of occupied hours a day, a week, a month and a year outside the limits of the specified category (Annex A and B).
Examples of methods to evaluate long term performance of building are given in Annex F
3% / 5% of period
Daily
Min.
3% %
Weekly
Hours
3% %
Monthly
Yearly
3% %
Working hours
Total hours
For design, dimensioning and long term evaluations some allowable deviations from the criteria both in space and time are recommended. Again from project to project or on national level other numbers can be fixed.

16. Indicators for the indoor environment
Design indicators
Measured indicators
Calculated indicators
As you have a yearly indicator for the energy use/demand of a building, you would also like to have an indicator for the indoor environment

17. Classification
For classification of the indoor environmnet a very simple way is just to list the design criteria

18. Classification based on occupants responses
Percentage
People finding the thermal environment acceptable 85
People finding the indoor air quality acceptable 80
Distribution of thermal sensation votes -3 -2 -1 +1 +2 +3 5 10 53 20 2
Distribution of temperature preference
Colder
Unchanged
Warmer 75
Another way is to ask the occupants directly about the indoor environment on a regular basis and use the results for a classification

19. Classification based on categories
A third method is to use the distribution of indoor temperatures and ventilation rate (or CO2 concentration) as a quality foot print of a given building or space. The data used can either come from long term measurements or building simulations program

20. Conclusions
Criteria for indoor thermal environment and ventilation rates are most important for the calculated energy performance
As the calculated energy requirements for new buildings are significantly depending on the used criteria for the indoor environment (room temperature, ventilation rates, lighting levels), the energy declaration (certificate) must include information on the indoor environment.
Difficult to express the quality of the indoor environment with one factor
More knowledge needed on the relative importance of thermal environment, indoor air quality, noise and light for peoples comfort and performance

21. More information More information and downloads: www.iee-cense.eu
Disclaimer:
CENSE has received funding from the Community’s Intelligent Energy Europe programme under the contract EIE/07/069/SI
The content of this presentation reflects the authors view. The author(s) and the European Commission are not liable for any use that may be made of the information contained therein.
Moreover, because this is an interim result of the project: any conclusions are only preliminary and may change in the course of the project based on further feedback from the contributors, additional collected information and/or increased insight.