SUSTAINABILITYSUSTAINABILITY

• The term “sustainability” is a very complex and ambiguous and in order to be approached correctly by an engineer it has to be clear defined and measurable. For example if you tell metaphors as “the planet is suffering”, it makes no sense to a scientist or engineer because planet cannot suffer in any commonly understood sense of the word.

• Engineers need rational facts as they are considered persons who solve problems, give solutions for the real problems. For this reason to enable solutions in such complicated spaces engineers and their methodologies are rather quantitative.

• According to some institutes, the building and construction industry uses 40% of the materials entering the global economy, consumes approximately 50% of the total energy supply and contributeswith almost 50% to the totalCO2 emissions released to the atmosphere through different stages, including construction, operation and demolition

• A sustainable construction develops the idea of low embodied energy, reduced greenhouse gas emissions, low operation and maintenance costs, responsibly sourced materials with recycled contents, durability, adaptability and comfort.

Certification Programs for the Evaluation of Building

Sustainability

German Sustainable Building Certificate (Deutsche Gütesiegel für Nachhaltiges Bauen DGNB)

• Founded in 2007, the German Sustainable Building Council together with the Federal Ministry of Transport, Building and Urban Affairs (BMVBS) developed a voluntary certification system for sustainable buildings the “German Sustainable Building Certificate”.

• The objectives of the DGNB are the development and promotion of sustainability in the planning, construction and operation process of a building. Sustainable building is environmental friendly, uses the resources efficiently, has an intelligent management with low life cycle costs, offers comfort and health to the users and fit optimally in the socio – cultural ambient.

The advantages of the German certificate are:• Active contribution to sustainability;• Cost- and Planning Certainty;• Minimizes Risk;• Praxis – oriented Planning Tool;• Focus on the Life Cycle;• Made in Germany;• Marketing Tool;• Comprehensive Quality of Property;• The performance is key;• More than “ Green Building”• Flexibility

LEED 2009 for New Construction and Major

Renovations

• Founded in 1993, the U.S. Green Building Council (USGBC) is a national nonprofit organization with over 19000 member companies and organizations, including corporations, governmental agencies, nonprofits and others from the industry.

• The aim of the USGBC was to define and measure the performances of “green buildings”.

• The Leadership in Energy and Environmental Design (LEED) Green Building Rating System is an internationally recognized green building certification system that evaluates environmental performances of a whole building over its life cycle.

BREEAM FOR OFFICES 2008

• With a history of over 90 years, the Building Research Establishment is a Governmental establishment in the UK.

• BREEAM (BRE Environmental Assessment Method) is one of the world’s leading and most widely used assessment methods for buildings.

• Aim of BREEAM is to reduce the impact of buildings on the environment, to enable buildings to be recognized according to their environmental benefits, to provide a credible, environmental label for buildings and to stimulate the demand for sustainable buildings.

• The sustainability of buildings is a very complex issue. It includes a lot of factors with clear defined relations.

By PhD. Prof. Eng. Corneliu Bob e.t.POLITEHNICA UNIVERSITY OF

TIMISOARA

PROPOSALS FOR THE BUILDING SUSTAINABILITY

Global model

• The global model is an evaluation tool, which combine the specific requirements of the three dimensions. It is based on a scoring system but the data used for accordance of points can be either qualitative or quantitative.

• To materialize the effects of the specific requirements, each of them is quantified with a score. The scores are accorded in function of calculated or evaluated value of each criterion.

• Table shows all the requirements with their corresponding scores.

• For a better understanding of each requirement, here comes an explanation what they refer to and how the scores are given:

Environment

• Initial embodied energy – 20p – the aim is to reduce the initial embodied energy and the emissions of CO2 related to the extraction, manufacturing, transport and demolition of building materials. The accordance of points is based on the energy demand per square meter of built area. In general the total initial energy incorporated in a building is a function of the main structural material. So buildings with a timber framed structure can obtain maximum points, followed by reinforced concrete, masonry and steel structures. For exact evaluation calculations have to be done.

• Operational energy – 20p – the aim is to reduce the operational energy consumption and the CO2 emissions associated with them. This parameter is related to the energy consumption for heating, cooling, air conditioning, hot water, refrigeration and lighting during the service life of the building. It can be evaluated in function of the necessary energy demand compared to the target value the building, taken from the Energy Performance certificate. Benchmarks have to be set in order to accord the credit points.

• Envelope – 20p – the aim is to minimize the energy demand for the space conditioning, to assure high thermal comfort and to avoid structural damage. Therefore materials with high quality shall be used for external walls, roofs and floors. The building envelope can be evaluated based on proper parameters like: Average heat transmission coefficient, Permeability, Air change rate, etc. If the envelope meets the minimum requirements 10points can be allocated. Additional points will we rewarded proportional.

• Renewable energy – 8p – the aim is to encourage the use of renewable energy sources as solar, wind, geothermal, etc. in order to supply a part of the nonrenewable energy. In this way environmental and economic impacts related to fossil fuel energy sources can be reduced

• Water consumption – 12p – the aim is to reduce the on – site and indoor potable water consumption from all sources, through the use of water efficient fittings, appliances and waterrecycling systems. Up to 12 points are awarded for achieving the performance target. The calculations are based on thepredicted average water consumption calculated in liter/person/day but also on the initial water consume for the erection of the building.

• Recycled materials – 8p – the aim is to reduce the environmental and economic impacts related to extraction and manufacturing of virgin materials. For materials with a recycled content of at least 24% the maximum points will be allocated.

• Renewable materials – 4p – the aim is to reduce the consumption and depletion of finite raw materials and long-cycle renewable materials by replacing them withrapidly renewable materials. This kind of materials are made from plantsthat are typically harvested within a 10-year or shorter cycle.

• Waste generation –4p – the aim is to reduce waste generation, related to construction site worksand to assure an efficient waste management plan. The plan must include measures which diverts construction and demolition debris from disposal in landfills and incineration facilities. One criterion for the allocation of points is based on the quantity of waste generated on site during construction andthe second criterion is related to the existence of a waste management plan.

• Heat island effect – 4p – the aim is to reduce the impact on microclimate and human environment.The type of roof and façade materials plays an important role in the enhancement of the heat island effect. Roofing materials with a high solar reflectance index (SRI) will be scored with 4 points.

Economic

• Initial costs – 25p–the aim is to reduce the overall costs of a building. Initial costs are related to the manufacturing of building materials, transport and manpower, but also to the acquisition of the installation systems. For a new building the initial costs are expressed in Euro/ square meter floor area.

• Operational costs – 25p – operational costs are as important as the initial costs. They are in strong relation with the operational energy consumption. The less energy is consumed for heating and cooling the less money is paid forthe bills. Beside this, the costs for maintenance and minor reparations also contribute to the overall cost.

• Erection time – 15p – beside good price and high quality the erection time is also very important for the beneficiary. The aim is to encourage the acceleration of construction works, but without affecting their quality. Buildings using prefabricated elements reduce the erection time, so maximum points can be accorded.

• Long service life – 17p – the aim is to realize buildings with long service life, in order to reduce all the impacts related to new constructions. It represents the life span of a building, or in case of rehabilitation the increase of its resistance. Typically the life span of a building is assumed to be 50 years without any refurbishments. In such circumstances the masonry and RC structures used to have a longer service life, so they get the maximum of 17p.

• Ease of Cleaning and Maintenance of the Structure – 8p – the aim is to extend the useful lifetime ofbuilding parts and layers of building parts, which can lead to lower maintenance costs.Proper documentation and a good technical planning of the building are needed to enableefficient cleaning and maintenance. If a user guide and instructions for maintenance and operations are available, 8 points can be allocated.

• Construction site and project management – 10p – the aim is assure an environmental friendly construction site and a well prepared project. To protect the environment and the health of all participants, construction sites must fulfill some important criteria: low waste, noise and dust generation. Proper documentation and plans has to be realized which take measures in order to limit this aspects. If all the documentation exists 10 points can be accorded.

Social

• Thermal comfort – 16p – the aim is assure an optimal thermal comfort for the occupants of the building. The main criteria which are needed to evaluate thermal comfort are: inner temperature, relative humidity, thermal gradient, air change. In this sense the envelope plays an important role because of its insulation, permeability and air tightness properties, but also the heating and cooling systems should be taken in consideration. The points will be accorded in function of the calculated PMV (Predicted mean vote) and PPD (Predicted percentage of dissatisfied)

• Daylight – 8p – the aim is to let natural lighting inside the building. In this way the monotony of the indoor environment can be disrupted and the consumption of electricity for lightning systems can also be reduced. Points will be allocated in function of the average daylight factorachieved in each room of the building. For example, a building, with an average daylight factor of 6% and direct access to natural light in each room, will gain 8 points.

• Air quality – 8p – the aim is to assure a good indoor air quality for the buildings’ occupants. In order to provide a good air quality, the materials used for finishing, paintings, adhesives and coatings must be odourless and with low emissions of volatile organic compounds VOCs. Another important factor is related to the ventilation systems. They have to provide a good air circulation, in order to eliminate all the unwanted smells and contaminants and to bring in fresh air.

• Noise and acoustic comfort – 8p – the aim is to create proper conditions assuring low level of interference and background noise. On the other hand it is also important to reduce the noise related to new buildings which can affect other buildings in the neighborhood. Two important parameters are evaluated: the airborne sound insulation values and the impact sound insulation values

• These can be determined either by testing or by Robust Details. Maximum points will be allocated for buildings which improve the values set in the performance standards. For example, if the airborne sound insulation value is with 9dB higher and the impact sound insulation value with 9dB lower, 8 points will be allocated.

• Structure safety – 20p – the aim is to protect the building occupants in case of extreme situations. After an earthquake most of the buildings will suffer some damages. The appearance of displacements, cracks or deflections in the building elements can lead to the destructionof the building. Structures have to be designed in such way, that they does not collapse under extreme loads.

• For existing structures built before 1970, as well for strengthening structures, the resistance to all actions (including extreme loads) should be over a minimum limit value, to be considered as safety. The failure probability Pf or reliability index βE can be considered as main parameters. For an optimal value of Pf = 10-6 or βE= 4.75 the maximum of 20 points will be allocated.

• Fire protection – 15p – the aim is to protect the occupants from the fire in buildings and from the toxic smoke caused by the fire. To allocate points, the quality of fire protection measures should be increased. The fire resistance of each element has to be in accordance with the performance standards, but also other issues as alarm, sprinkler, smoke evacuation systems and evacuation plans has to be taken in consideration.

• Adaptability and area efficiency – 15p – the aim is to design buildings which can be adapted to different requirements and destinations without high investments. It is important to create structures with high area efficiency, flexibility and adaptability. A good adaptability offers the possibility to modify the inner architecture, in order to have an optimal place use. The buildings with framed structures may get a maximum score (15p) for adaptability, because the separation walls can be placed optional, without risking the structure safety.

• System efficiency and control – 14p – the aim is to provide systems with high efficiency in order to reduce the impacts related to their use and to assure an optimal control of these systems for the buildings occupants. All energy systems should be in accordance to the CEE directives and should present an energetic certificate. On the other hand, heating, lighting and cooling systems should be provided with individual controls in order to be adjustable for personal needs and preferences.

• Maximum points will be allocated if the optimum values for each criterion are met. The optimal reference values are given in Table, as an example applied to a family dwelling. Achieving these targets would result in an ideal solution, which would meat all the sustainability performances of a building. The values presented in the example are only indicative and may be different from case to case.

• Compared to the other certification tools, the global model proposed by the authors has the aim to ease the decision making of a civil engineer. The criteria evaluated in the global model are mostly related to the tasks that a civil engineer has to do. Other aspects, like site selection and architectural value of site are also important, but not for a civil engineer.

A comparison has been realized between the three certification tools (DGNB, LEED and BREEAM) and the

global model. Model\Dimension Ecological Economic Social Total

DGNB 29.2% 31.3% 21.8% 82.3%

LEED 58% - 18% 76%

BREEAM 49.85 10.8 23.82 78.22%

Global model 40% 30% 30% 100%

SPECIFIC MODEL

• A building sustainability index S, based on the global model presented in the previous chapter has been established. The building sustainability index includes the quantification of measurable objectives that characterize the full life cycle of buildings.

To combine the effects of the three dimensions – ecological,

economic and social, on the entire building sustainability, a simple quantitative equation has been

proposed

• Where:• BSI – building sustainability index;• Se, Sf, Sp, - building sustainability indexes for the

ecological, economic and social dimensions;• αe, αf, αp, - coefficients indicating the percentage

of participation to the building sustainability of the three dimensions;

• ER, FR, PR, - reference values for the components of the ecological, economic and social dimensions;

• E, F, P – the values of the components taken into account for the three dimensions.

BSI=S e+S f +S p=αeE R

E+α f

F R

F+α p

P R

P

For instance the building sustainability index for the ecological dimension can

be considered as follows:

• and En – total embodied energy (initial and operational)of the reference and studied building;

• WR and W – water consumption of a reference and studied building;• andMl – renewable materials used by the reference and studied building;• and Be – specific parameters of the reference and studied building

envelope • αen,αew,αem,αeb – coefficients indicating the percentage of participation to

the building sustainability of the total energy, water consumption, renewable materials and building envelope.

Se=αenE nR

En+αew

W R

W+αec

M l

M lR+αeb

BeR

Be

αe= αen+αew+αem+αeb

The building sustainability index for the economic dimension can be

considered as follows:

S f =α fcC R

C+α ft

T R

T+α fl

L

LR

αf= αfc+αft+αfl

CR and C – total costs (initial and operational) of a reference and studied building;TT and T –the erection time of a reference and studied building;LR and L – long service life of the reference building as compared with the studied building;αfc+αft+αfl – coefficients indicating the percentage of participation to the building sustainability of the total costs, erection time and long service life.

The building sustainability index for the social dimension can be

considered as follows:

S p=α pthThR

T h+α pq

Q

Q R+α pr

RR

R+α pf

F

F R

αp= αpt+αpq+αpr+αpf

TRh and Th – thermal comfort for a reference and studied building;

QR and Q – includes the interior comfort (daylight, air quality, noise and acoustic comfort) of a reference and studied building;

RR and R – structure safety of a reference and studied building;FR and F – fire protection of a reference and studied building;αpt+αpq+αpr+αpf - coefficients indicating the percentage of

participation to the building sustainability of the thermal comfort, interior comfort, structure safety and fire protection.

ThR

The reference values ER, FR and PR can be taken either as the minimum values of the calculated solutions or as optimal and mandatory values according to standards or other sources.

The distribution of the coefficients was established arbitrary, in function of the importance of the parameters:

αe=40% (0.4)

αf =30% (0.4)

αp=30% (0.3)

• The building sustainability index BSI, presented, is a way to use multiple criteria in relation to project decision – making. Even for smaller number of measurable values, using the BSI will simplify the appreciation of sustainable development and will confer a positive contribution to obtain optimum design solutions and facility operations.