Summer comfort and cooling - Workshop AIVC 2009

Tuesday 31 March 2009
13.00 Opening of registration
14.00 Opening of workshop – session 1 - Chairmen: M. Santamouris and J. Cipriano

Many southern European countries are finding that peak summer electricity consumption now exceeds that of the traditional winter peak demand. This reflects the growing trend for building occupants to install air conditioners for cooling. There is now deep concern that this steadily growing demand for cooling energy cannot be met. Matters are made worse by the characteristic peak midday demand for cooling energy.

To address this problem and develop solutions, the International Network for Information on Ventilation and Energy Performance (INIVE) undertook a workshop on Summer Comfort and Cooling which was held in Barcelona, Spain on 31st March to 1st April 2009. Experts from several countries were invited to make presentations. In addition to country presentations, various related projects and organisations concerned with cooling technologies were introduced. The purpose of this Editorial is to outline the information presented at this meeting.

The objectives of the meeting were set out by Prof. Mat Santamouris of the National and Kapodestrian University of Athens, Greece. He emphasised that buildings account for almost 40% of the world’s energy use and 50% of CO2 emissions. The number of air-conditioning units in homes has increased by a significant amount. In 2000, residential air conditioning accounted for about 6.4% of total electricity consumption in OECD countries, representing a rise of 13% between 1990 and 2000. About 46% of OECD households have some air conditioning. This includes 80% of all new American homes, the majority of Japanese homes and 23% of Australian homes. Current estimates for European Union homes is 5-7% but this is rising rapidly and the market is nowhere near saturated. The drivers for growth include:

The two key overall objectives of this workshop were to understand the present growth in cooling demand in INIVE countries and to learn from the experiences of each country on how the demand for cooling energy can be moderated.

The country presentations provided an opportunity to compare problems and solutions.

Portugal became one of the first countries in Europe to introduce measures to limit cooling demand within its building energy regulations of 1990. This covered design measures to limit cooling load including statutory requirements for outdoor solar shading. Design requirements also included the need for thermal mass combined with night cooling by ventilation. These design requirements were aimed at limiting periods of overheating to just the hottest periods during summer. A reference building concept was used to compare improvements to cooling performance against a common set of criteria. In 2002 Portugal adopted the EPBD (see Appendix 1) but the reference building approach was dropped and replaced by setting criteria for a maximum level of primary energy consumption. To account for different climatic areas, Portugal was divided into three climatic zones and the allowable primary energy consumption was set according to the zone. Cooling needs were calculated on the basis of EN ISO 13790 (see Appendix 2). Designers can also choose more accurate software that satisfies ASHRAE Standard 150.

At the construction stage, performance is necessarily based on calculation but energy monitoring is required over a three year period after which remedial action is required if the promised energy performance is not fulfilled.

The climate in Finland is much cooler than southern Europe but, nevertheless, cooling is widely used in office buildings. Finland recognises a strong link between indoor climate and productivity. High ventilation rates combined with maintaining comfort temperature are shown to lead to enhanced productivity that vastly outweighs the extra energy cost. The objective therefore is to meet this demand with the minimum of impact on the environment. Thermal energy calculations in relation to comfort temperature and adaptation are based on EN15351 (see Appendix 2). The Finnish Building Code, in general, requires:

That window area is limited –max 15% of floor area and 50% of façade area;
Solar shading and selection of glazing;
The control of lighting and other internal heat loads;
Thermal insulation: walls U < 0.17 W/m².K;
The use of thermal capacity;
Night time ventilation for cooling;
Ground source cooling;
Water source cooling (lakes, sea water);
High performance mechanical cooling.

To achieve good, year round, energy performance, ventilation heat recovery is required in all new buildings.

3.3 Czech Republic (Presented by Karel Kabele Czech Technical University of Prague)

Requirements in the Czech Republic are currently restricted to non-residential buildings. The maximum building temperature for air-conditioned spaces is set at 28°C and at 31.5°C for non air conditioned spaces. Summer overheating is especially a problem with new highly insulated buildings aimed at preventing winter heat loss.

Alternative low energy cooling solutions currently being assessed include: night cooling; solar cooling; evaporative cooling; earth heat exchangers; underground water; passive cooling.

At present night ventilation and passive cooling are seen as difficult to implement due to security problems. Also there are control difficulties. Therefore mechanical cooling is becoming more widespread. Current research is looking at radiant heating and cooling for offices and dwellings using radiant ceiling panels. Analysis shows that winter heating needs can be fulfilled but some problems with cooling may occur, including insufficient cooling capacity and a risk of occasional short-term condensation as well as limitations in buildings with high internal heat gains. .

Israel experiences high summer heat conditions and strong demand for summer cooling. In principal air conditioning is discouraged but increasing wealth, combined with demand for thermal comfort, means that there is a high penetration of air conditioning in dwellings (60-70%) as well as in non-residential buildings. This has resulted in increased demand for electricity and peak load problems. Air conditioning energy accounts for approximately 12% of annual energy consumption and 25% of peak morning demand. To counteract this, Israel has developed a Green Building Standard. Buildings reaching good levels of environmental performance can be classified as ‘green’ or ‘outstandingly green’. This is being complemented by a new energy code and energy rating scheme. Much emphasis is also being placed on renewable energy, particularly solar systems. Ice storage schemes are also being used in an attempt to reduce peak cooling loads.

The Netherlands first introduced Energy Performance Regulations in 1995. These are aimed at new residential and non-residential buildings to cover the performance of heating, cooling, ventilation and hot water. Energy performance requirements are gradually strengthened each year or so, following improvements in technologies. Currently energy performance requirements are the same for air conditioned and non air conditioned buildings. In the case of air conditioned buildings this is difficult to achieve. Calculations for the energy needed for cooling are based on EN ISO 13790 (see appendix 2). Currently the Dutch regulations do not address thermal comfort and it is not possible to set a minimum requirement for summer comfort in the energy performance calculations. A building can therefore still be designed with poor summer comfort. However, it is increasingly recognised that users are introducing mechanical cooling into spaces even if it is not part of the original design. Therefore the concept of ‘fictitious cooling” has been introduced on the assumption that cooling may be introduced at a later date. This resulting cooling energy is incorporated into the overall energy performance assessment of the design.

The UK energy strategy has focused on reducing carbon emissions. Air conditioning is currently not the largest contributor to the environmental impact of buildings but it is increasing and is thus a concern. A reference building approach is used equivalent to a building that satisfies the 2002 Part L Energy Regulations. New buildings must demonstrate a prescribed improvement over the reference building of approximately 28% for air conditioned buildings and 23% for naturally ventilated buildings. Much reliance is placed on case studies to demonstrate good solutions to passive cooling. Results show that passive measures generally work well. There are some generic difficulties including overheating of top floors, insufficient ventilation controls, poor interface with building management systems and difficulties in providing passive cooling in spaces occupied for 24 hours a day.

In Belgium, lack of compliance with Building Energy requirements at the construction stage has been identified as a severe problem. In order to achieve better results with implementation of the EPBD (see Appendix 1), a third party rapporteur must certify that the requirements have been correctly implemented. This independent reporting must also state the extent to which requirements have or have not been met. Non-compliance results in a significant fine to the building owner which is directly proportional to the transgression. Incorrect reporting will also result in a penalty.

In relation to overheating, Belgium has a mild climate with a long-term summer average of no more than 18°C and very few hours above 25°C. Thus overheating is a result of solar and indoor heat gains. The concept of an “overheating indicator” is used to identify the risk of overheating. This is based on the number of degree hours over comfort temperature where the comfort temperature itself is adaptive and hence can vary. The value of this indicator is determined on the basis of ISO EN 13790 (Appendix 2) calculations and the maximum permitted value is 17500 Kh (degree hours). If designs or buildings exceed this value then the owner will be subject to a penalty. At present a fixed rather than variable intensive ventilation rate for cooling is applied to the calculation. This is currently being reviewed to promote wider use of ventilation for cooling. As in the Netherlands, Belgium uses the “fictitious cooling” concept i.e. the probability of consumption for cooling is taken into account in anticipation of subsequent installation of mechanical cooling. This allowance is based on the value of the overheating factor. At values up to 8000 Kh no cooling is assumed to be needed whereas as for values at the maximum permitted there is a high probability that cooling will be used. This approach prevents the designer from avoiding making an allowance for air conditioning in the energy calculation in a building design that has a high probability of overheating. Solar protection devices are an important component of overheating prevention and therefore there are financial incentives for solar shading.

In Athens the number of hours that the temperature exceeds 30°C each year has increased over the last 30 years by 30 – 40%. This high temperature can occur for the whole day. This is as a result of climate warming and of the establishment of urban heat islands. Based on a set point temperature of 27°C, peak electricity consumption is predicted to increase by 300% while city centre cooling demand will increase by 130%. This rise in temperature also impacts on the COP of room air conditioners which is estimated to fall by 25%. Low-income homes are the least prepared for efficient cooling because they lack the construction quality necessary for benefiting from efficient cooling. Such householders therefore suffer a much greater burden.

To limit energy demand, various actions have been introduced. This includes controls on the U values of building components and maximum annual energy consumption for new and refurbished buildings. For existing public buildings there are mandatory requirements based on the use of passive cooling. All air conditioning equipment must be inspected annually and all buildings should satisfy the Class B specification of EN 15251 (Appendix 2). Cool coatings must be used on roofs and external walls of public buildings and ceiling fans have to be installed.

Emphasis is being placed on passive cooling including night ventilation, external solar shading, shading of air conditioning plant when used, vegetative cover of roofs where possible, heat recovery from condensers and exhaust ventilation air, the application of adaptive thermal comfort and the use of ceiling fans.

Spain has a variable climate. Severe winters occur in the middle and north of the country while hot summers occur in the centre and south of the country. Historically passive cooling was widespread but 20th century buildings have been constructed without much consideration for energy efficiency. The use of air conditioning is now widespread and Spain consumes more energy per inhabitant for cooling than anywhere else in Europe. Peak summer loads are forcing an increase in the number of power stations and the size of the electricity grid. Although the use of air conditioning in dwellings is small (about 2% of the overall cooling energy consumption) this is rising dramatically.

Requirements for Spain are covered by the Spanish Building Code and a building energy labelling scheme. For energy labelling, the cooling and heating demand (energy and CO2 emissions) of the building is estimated and is compared against a reference value for an equivalent sized building. Good energy performance is awarded by the classification of an energy label. Improvements can be achieved by U value, external solar shading, window quality, and internal load limitations. Cooling load is based on the energy required to maintain an indoor temperature below 27°C. Future trends are aimed at developing low energy cooling technologies. Recent monitoring of apartment buildings has shown that significant cooling energy consumption reduction is possible by introducing simple cross flow night ventilation techniques. Further passive solutions include: natural ventilation with solar chimneys; thermal inertia with night ventilation; night radiative cooling; buried pipes; evaporative cooling; PV ventilation; phase change materials.

Italy experiences the same problems as other Mediterranean climates including: urban heat islands, peak electricity demand in summer and a huge growth in the number of air conditioning units. Where possible, passive solutions are being identified with a preference for natural ventilation. Solar shading is compulsory along with performance requirements for glazing systems, thermal mass and thermal transmittance. Other solutions include the use of ‘cool’ paints, vegetation, restrictions on total primary energy use and the adoption of an informal dress code.
In conjunction with other countries, a proposed new Passivhaus Standard for Warm European Climates has been developed. This covers specific comfort objectives and energy limits for both winter and summer. It specifies that:

Energy need for heating shall be lower than 15 kWh/m².year;
Energy need for cooling: shall be lower than 15 kWh/m².year (this value may be updated and possibly reduced based on field studies);
Total primary energy shall be lower than 120 kWh/m².year.

Summer comfort requirements have been included in French Regulations since 2000, while energy efficiency requirements for cooling were introduced in 2005. France is divided into eight climatic regions varying from a predominantly heating demand in the north to a predominantly cooling demand in the south. Where a building can be passively cooled, any energy used for mechanical cooling must be balanced by reductions in energy use elsewhere. A summer comfort criterion is based on the operative temperature for the warmest hour during occupancy. In many cases this criterion must be satisfied by passive means whether or not the building has air conditioning. Low inertia buildings are not possible for summer comfort. Passive cooling measures include solar protection (including overhangs, use of colours, and insulation), green roofs and ventilation for cooling (including passive night cooling and mechanical night ventilation). For EPBD calculations an upper energy limit of 50 kWh of primary energy use for each m² of floor area is being included in the 2011 Regulations for non-residential buildings.

In Germany, the air conditioning of dwellings is only necessary in poorly designed buildings with high internal and solar heat gains, and where occupants are intolerant to high temperature. Similarly, in non residential buildings, cooling becomes a problem in buildings with high ratios of glazed windows and high internal heat gains. Legislation covers limitations on primary energy use including cooling energy. Maximum acceptable indoor comfort temperatures vary between 25 – 27°C according to climate region. These temperatures must not be exceeded for more than 10% of the occupied time based on 24 hours/day for dwellings and 10 hours/day for offices. There are also limitations on permissible solar gain. Future plans are addressing solar cooling, passive cooling, adiabatic cooling, earth coupled systems and the use of renewable energy for cooling. The Fraunhoffer Institute is also producing guidance on Requirements in EU Member States related to Summer Comfort and Energy Consumption for Cooling.

The Intelligent Energy – Europe (IEE) programme is aimed at making Europe more competitive and innovative while, at the same time, helping it to deliver on its climate change objectives. It is run on behalf of the European Commission, and seeks to bridge the gap between EU policies and how they impact on the ground.

Funding is available from the IEE for projects that have a significant impact on the market and cover:

Knowledge transfer from one part of the European Union to another on how to do something or how to improve processes;
Helping the different decision making organisations understand each other better;
Building confidence and understanding in the market, which is essential to the sector’s growth.

Various IEE sponsored projects address the field of low energy cooling and building energy efficiency. A number of these were included in the workshop presentation and are outlined below.

4.1 Assessment and Improvement of the EPBD Impact (for new buildings and building renovation) ASIEPI (Presented by S Alvarez, University of Seville, Spain) www.asiepi.eu

This project is supported by 17 EU countries and assists in the implementation of the EPBD (see Appendix 1). An important task is to assess how EU countries integrate summer comfort and energy use for air conditioning into their energy performance calculations. So far many misunderstandings have been identified with no common approach. At present, important passive cooling methods may be ignored or not adequately incorporated into cooling calculations. ASIEPI seeks to resolve these issues. Various passive cooling measures are being compared and guidance is being produced on passive cooling methods.

4.2 Building Advanced Ventilation Technological IEE ADVENT Programme (Presented by Andrew Cripps, Buro Happold, UK) www.buildingadvent.com

ADVENT is a European project aimed at producing examples and case studies to demonstrate energy savings for acceptable indoor air quality and thermal comfort in different European climatic regions. Participating countries are Denmark, Finland, Greece, Portugal and the United Kingdom. It is aimed at encouraging the use of low energy ventilation systems by disseminating information on buildings that incorporate low energy techniques. The purpose is to help overcome a general lack of knowledge and confidence amongst engineers and architects. Technologies being incorporated in some of the case studies include phase change materials, radiative cooling and groundwater heat pumps.

4.3 IEE Cool Roofs Project (Presented by Mat Santamouris NKUA Greece) www.coolroofs-eu.eu

Reflective materials have a dramatic impact on improving the urban microclimate and reducing the impact of urban heat islands. Used extensively, highly reflective coatings on buildings are able to increase albedo (from 0.2 to 0.85), decrease the need for air conditioning and decrease the number of hours of overheating discomfort. The performance of coatings is being extensively researched and increasingly well understood. The overall aim of this project is to implement an action plan for cool roofs in the EU aimed at taking advantage of existing knowledge and results of the latest research.

This work is being coordinated by the National and Kapodestrian University of Athens with partners in Belgium, France, Italy and the UK.

HARMONAC addresses the practical issues arising from the need for regular inspections of air-conditioning systems of over 12 kW cooling capacity as required by EPBD. This requirement will put a significant resource and cost burden on EU Member States which could, potentially, lead to poor implementation of the Directive if the links between costs and benefits are not fully demonstrated. The primary aim of the HARMONAC project is therefore to provide a robust source of information on the energy and carbon savings to be made from various aspects of the A/C inspection process, together with the time required and the relative costs. Results are based on nearly 600 inspections and 40 case studies with accompanying energy consumption measurements. The project will also provide guidance on the frequency of inspection required to achieve various levels of energy savings in various system types and sizes.

The project is lead by the Welsh School of Architecture, Cardiff University in the UK and partner organisations come from Austria, Belgium, France, Greece, Italy, Portugal and Slovenia.

4.5 Summer Comfort and Cooling (IEE ThermCo Project) (Presented by J. Pfafferott, Fraunhoffer IBP, Germany) www.thermco.org

ThermCo evaluates low-energy cooling concepts all over Europe using a standardised method based on existing monitoring data from best practice examples. It also provides design guidelines for typical building concepts in the European climate zones for architects and HVAC engineers.

Results have shown that it is possible to go beyond the energy requirements of existing legislation while obtaining good thermal comfort. However, there is strong uncertainty in day-to-day practice due to the lack of legislative regulations for mixed-mode buildings which are neither entirely naturally ventilated nor fully air-conditioned. This work will provide a knowledge pool for passive and low-energy cooling techniques and, hence, will contribute to reduced cooling energy demand, a better indoor environment and cost-effective building concepts.

The lead organisation is the Fraunhoffer Institute for Solar Energy, Germany with participants from the Czech Republic, Denmark, Finland, France, Greece, Italy, and Romania.

Various European Associates are contributing to the development of low energy cooling products. Those presenting information at the workshop are included below.

5.1 EURIMA - European Insulation Manufacturers Association (Presented by J. Solé Bonnet) www.eurima.org

Insulation plays an important role in reducing energy demand. In winter it protects the building from heat loss. Equally, during hot summer days when the outdoor temperature exceeds comfort values, it protects the building from transmission heat gain. EURIMA provides information on the effective use of insulation.

5.2 European Alliance of Companies for Energy Efficiency in Buildings EUROACE (Presented by E. del Pino, URSA Insulation) www.euroace.org

EuroACE was founded in 1998 by 20 of Europe’s leading companies involved with the manufacture, distribution and installation of energy saving goods and services. It evolved in response to the fact that Europe's 160 million buildings are responsible for well over 40% of greenhouse gas emissions within the EU and that the greenhouse gas emission prediction potential for buildings is considerable. The mission of EuroACE is to work together with the European institutions to help Europe achieve greater sustainable energy use in buildings and significant reductions in carbon dioxide emissions. Energy efficiency measures for cooling is seen as an important area and much activity is focused on the passive solutions needed to minimize or avoid completely the use of air conditioning.

5.3 European Solar Shading Organisation ES-SO (Presented by W.Beck) www.es-so.com

This is an umbrella organisation for the solar shading industry in the EU and has members in 15 countries. Its purpose is to stress the value of solar shading for cooling and to demonstrate energy savings at the EU level. In summer, shading is effective at minimising the need for mechanical cooling while in winter, it can improve window insulation. Systems can also maximise the benefit of reducing glare while permitting the use of natural daylight. Considerable effort is being made to reduce barriers to the use of shading.

5.4 International Building Performance Simulation Association IBPSA (Presented by J. Hensen) www.ibpsa.org

Simulation plays a pivotal role within the EPBD and within the entire building energy performance industry. IBPSA is a non-profit international society of building performance simulation researchers, developers and practitioners, dedicated to improving the built environment. IBPSA operates throughout the world through affiliate organisations. It organises conferences and produces the Journal of Building Performance Simulation (JBPS).

On behalf of the manufacturing industry, Ansgar Thiemann from Daikin gave a presentation on how manufacturers are responding to meeting building cooling and energy efficiency needs. This showed a very strong and responsive market that is adapting to demand for passive and low energy cooling through an extensive programme of applied research and product development.

Most countries expressed concern and understood that the growing use of mechanical cooling in buildings could not be matched by increasing conventional electricity supply. Apart from increased greenhouse gas emissions, a particular problem is the need to satisfy the characteristic peak load requirement of cooling systems.

Reasons for cooling demand largely result from high internal gains combined with architectural or building designs that trap heat within the building.

Since high temperature environments can present a health as well as discomfort problem, criteria defining acceptable summer comfort conditions are being developed. This is important progress which will help to define conditions for cooling.

Many passive cooling solutions were presented which can either eliminate or significantly reduce the need for mechanical cooling. At present, fully air conditioned buildings tend to be isolated from the outdoor environment and often cooling needs to be operating even when outdoor temperatures are at or below comfort levels. This approach does not fulfil environmental objectives. In some instances, current Regulations tend to focus on improving the energy efficiency of air conditioning systems rather than addressing the need to avoid or substantially downsize them in the first place.

Countries already experiencing increasing demand for cooling energy have adopted Regulations to ensure that passive measures are implemented before any additional cooling need is met by mechanical means. This meeting provided the opportunity to learn from such experiences. There is clearly much to be gained from the methods now being introduced.

There is no doubt that those presenting information at this meeting had the technical solutions to provide cost and energy effective cooling solutions.

In Europe, as elsewhere in the world, there is a strong demand to reduce energy use, both to mitigate CO2 emissions and to strengthen security in supply. In the case of buildings in European Union Member Countries this is managed through the Energy Performance of Buildings Directive (EPBD Directive 2002/91/EC). This requires member states to apply minimum requirements covering the energy performance of new and existing buildings. The EPBD therefore plays a major role in forming building energy policy in the EU and hence featured widely in the presentations. The Directive requires:

A common methodology for calculating the integrated energy performance of buildings;
Minimum standards on the energy performance of new buildings and existing buildings that are subject to major renovation;
Systems for the energy certification of new and existing buildings and, for public buildings, prominent display of this certification and other relevant information. Certificates must be less than five years old;
Regular inspection of boilers and central air conditioning systems in buildings and, in addition, an assessment of heating installations in which the boilers are more than 15 years old.

The common calculation methodology must include all aspects that determine energy efficiency and not just the quality of the building's insulation. This integrated approach should take account of aspects such as heating and cooling installations, lighting installations, the position and orientation of the building and heat recovery, etc.

Some countries have based minimum standards on a reference building approach in which a specified minimum improvement over an equivalent “reference building” is required. However, this has led to anomalies that can result in air conditioning being used even when it is shown to be far more energy intensive than an equivalent passively cooled buildings providing the same level of comfort. Some countries have avoided the reference building approach and based requirements on an actual energy target irrespective of the means by which this is achieved. In such cases an allowance or ‘fictitious’ cooling amount is often factored into the energy design calculation to discourage a low energy solution that subsequently requires air conditioning to meet comfort needs. In other words, if a design is shown to not reasonably fulfil summer thermal comfort requirements, an allowance for subsequent cooling energy must be factored into the energy estimate, even if a cooling system is not included in the initial construction. Evaluation is largely based on approved calculation methods followed by energy monitoring of the actual building once constructed.

Various European Standards were mentioned throughout the country presentations. Key Standards are summarised below.

European Standard and International Standard ISO EN 13790:2008 “Calculation of Energy Use for Heating and Cooling”

This calculation standard has been used as the basis of simplified energy calculation for estimating cooling (and heating) energy in several of the countries presenting material at this workshop. In these countries it has become the standard model required by the EBPD. Full details are available from ISO
http://www.iso.org/iso/iso_catalogue/catalogue_tc/catalogue_detail.htm?csnumber=41974

Calculation method for assessment of the annual energy use for space heating and cooling of a residential or a non-residential building or a part of it.
The calculation is based on:

The heat transfer by transmission and ventilation of the building zone when heated or cooled to constant internal temperature;
The contribution of internal and solar heat gains to the building heat balance;
The annual energy needs for heating and cooling, to maintain the specified set-point temperatures in the building – latent heat not included.

The Standard also gives an alternative simple hourly method, using hourly user schedules (such as temperature set-points, ventilation modes or operation schedules of movable solar shading).
The calculation procedure is restricted to sensible heating and cooling but methods are given for calculating energy use due to humidification and dehumidification.
Applicable to buildings at the design stage and to existing buildings.
Protocols to specify the type of sources of information and the conditions when they may be applied.

CEN EN15251, Indoor Environmental Input Parameters for Design and Assessment of Energy Performance of Building

This standard specifies how design criteria can be established and used for dimensioning of systems. It defines how to establish and define the main parameters to be used as input for building energy calculation and long term evaluation of the indoor environment. The standard also takes into account issues not previously dealt with including differing occupant expectations in relation to naturally ventilated and air conditioned buildings.

Calculation method for assessment of the annual energy use for space heating and cooling of a residential or a non-residential building or a part of it.
The calculation is based on:

The heat transfer by transmission and ventilation of the building zone when heated or cooled to constant internal temperature;
The contribution of internal and solar heat gains to the building heat balance;
The annual energy needs for heating and cooling, to maintain the specified set-point temperatures in the building – latent heat not included.

The Standard also gives an alternative simple hourly method, using hourly user schedules (such as temperature set-points, ventilation modes or operation schedules of movable solar shading).
The calculation procedure is restricted to sensible heating and cooling but methods are given for calculating energy use due to humidification and dehumidification.
Applicable to buildings at the design stage and to existing buildings.
Protocols to specify the type of sources of information and the conditions when they may be applied.

CEN EN15251, Indoor Environmental Input Parameters for Design and Assessment of Energy Performance of Building