Passive solar systems for building renovation ERASMUS IP Sustainable Refurbishment, Retrofit, Energy Management in Housing Passive solar systems for building renovation Maria Isabel Abreu isabreu@ipb.pt 19th May, Corte

In passive solar building design, windows, walls, and floors are made to collect, store, and distribute solar energy in the form of heat in the winter and reject solar heat in the summer This is called passive solar design because, unlike active solar systems, it doesn't involve the use of mechanical and electrical devices. The key to designing a passive solar building is to best take advantage of the local climate

These technologies: - convert sunlight into usable heat (water, air, thermal mass) cause air-movement for ventilating protect from sunlight with little use of other energy sources Passive heating use Passive cooling use (reduce summer cooling requirements)

integration passive solar SOLUTIONS IN Building renovation It is recognized that the construction technologies for renovation are relatively new and, unfortunately, most R&D and products development is directed toward new construction There are some passive solutions that are possible to apply With the propose of reaching similar energy performance requirements as those established for new buildings, it is possible to adopt in existent buildings a range of passive energy-renovation-solutions

Key passive solar building design concepts Direct solar gain Indirect solar gain South facing glass Isolated solar gain Thermal mass to absorb, store, and distribute heat Insulation and glazing Passive cooling

Direct gain, indirect gain and isolated gain/Thermal mass The goal of all passive solar heating systems is to capture the sun’s heat within the building’s elements and release that heat during periods when the sun is not shining At the same time that the building’s elements (or materials) is absorbing heat for later use, solar heat is available for keeping the space comfortable

Direct solar gain The actual living space is a solar collector, heat absorber and distribution system South facing glass admits solar energy into the house where it strikes directly and indirectly thermal mass materials such as masonry floors and walls The direct gain system will use 60–75% of the sun’s energy striking the windows

Direct solar gain/Heat storage The ratio of solar exposed glass to exposed thermal mass in a room is critical and varies significantly between climates and designs Too much thermal mass for the available solar heat input creates a heat sink and increases auxiliary heating needs. Insufficient thermal mass causes daytime overheating and rapid heat loss at night Use 6 to 9 m2 of living space floor area for each 1 m2 of south glazing area

Indirect solar gain Thermal mass is located between the sun and the living space The thermal mass absorbs the sunlight that strikes it and transfers it to the living space by conduction and convection The indirect gain system will use 30–45% of the sun’s energy striking the glass near the thermal mass wall Efficiency can suffer from slow response (thermal lag) and heat losses at night

Indirect solar gain/Heat storage Thermal storage walls – Trombe walls

Isolated solar gain Have its integral parts separate from the main living space The system use solar energy to passively move heat from or to the living space using a fluid, such as water or air by natural convection or forced convection The isolated gain system will use 15–30% of the sunlight striking the glazing toward heating the adjoining living areas Sunrooms Convective loop through an air collector to a storage system inside the building

Isolated solar gain Sunrooms Convective loop through an air collector to a storage system inside the building

Sunrooms Use a dark color for the thermal wall The thickness of the thermal wall should be 20-30 cm for adobe or earth materials, 25-35 cm for brick, 30-45 cm for (dense) concrete For a sunroom with a masonry thermal wall, use 0.30 m2 of south glazing for each m2 of living space floor area Have a ventilation system for summer months If overhead glass is used in a sunroom, use heat reflecting glass and or shading systems in the overhead areas

Insulation Thermal insulation is the reduction of heat transfer between objects in thermal contact or in range of radiative influence Thermal insulation can be achieved with specially engineered methods or processes, as well as with suitable object shapes and materials Thermal insulation provides a region of insulation in which thermal conduction is reduced or thermal radiation is reflected rather than absorbed by the lower-temperature body

Special glazing systems Insulated glazing more commonly known as double glazing (or double-pane, and increasingly triple glazing/pane) are double or triple glass window panes separated by an air or other gas filled space to heat transfer across a part of the building envelope

Preventing heat from entering the interior (heat gain prevention) Passive cooling Passive cooling is a building design approach that focuses on heat gain control and heat dissipation in a building in order to improve the indoor thermal comfort Preventing heat from entering the interior (heat gain prevention) Removing heat from the building (natural cooling).

Passive cooling Solar control A properly designed shading system can effectively contribute to minimizing the solar heat gains Shading both transparent and opaque surfaces of the building envelope will minimize the amount of solar radiation that induces overheating in both indoor spaces and building’s structure The heat gain captured through the windows and envelope will be reduced

Window coverings Window coverings are material used to cover a window to manage sunlight Curtains / Drapes Window blinds Venetian blinds: Wood, Faux Wood, Vinyl, Aluminum Mini blinds Shutters Window Shades, including: Roman & Folding Shades Roller Shades Solar screen

Window coverings

Passive cooling A solar chimney or thermal chimney A simple description of a solar chimney is that of a vertical shaft using solar energy to enhance the natural stack ventilation through a building Is a way of improving the natural ventilation of buildings by using convection of air heated by passive solar energy

Passive cooling Sunrooms can also be designed to perform this function With the connecting lower vents to the living space open along with windows on the north side, air is drawn through the living space to be exhausted through the sunroom upper vents

Passive solar lighting Passive solar lighting techniques enhance taking advantage of natural illumination for interiors, and so reduce reliance on artificial lighting systems This can be achieved by careful building design, orientation, and placement of window sections to collect light The use of reflecting surfaces to admit daylight into the interior of a building Window sections should be adequately sized, and to avoid over-illumination can be shielded with a brise soleil, awnings, well placed trees, glass coatings, and other passive devices

Existing brick walls often have adequate thermal mass Opportunities for improving or adding passive solar design features when renovating an existing building Existing brick walls often have adequate thermal mass Insulate external walls, ensure that thermal mass is balanced by increased solar access, and design openings and convective flow paths to ensure that additional solar gains are distributed effectively Renovation

Increase existing insulation levels and insulate any previously uninsulated ceilings and walls (and floors in cool climates) while they are exposed or during re-cladding or re-roofing. Design additions to allow passive solar access and facilitate movement of passive heat gains to other parts of the house Renovation Use high performance windows and glazing for all new windows and doors Replace poorly performing windows where possible Relocate poorly orientated or oversized windows and increase the size of solar exposed south windows Implement dark external floor finishes

And more… Seal existing windows and external doors, and replace warped or poorly fitted doors Double glaze windows to reduce winter heat loss Renovation Create airlocks at entrances in cool and cold climates Reorientate as much of the living space as possible to the south side South-facing bedrooms can become living rooms Add doors and walls to create zones with similar heating needs Consider adding a sunroom to maximize solar gains in cool climates

Solar passive solutions compatible with existent and historic buildings architecture Direct solar gains In summer is possible to use internal movable insulation, ensuring air circulation between this device and the window

Thermal mass wall behind a window (Trombe wall) Solar passive solutions compatible with existent and historic buildings architecture Thermal mass wall behind a window (Trombe wall) The integration is possible in existing windows or doors that are not usually opened, preserving existing materials and outside appearance

Solar passive solutions compatible with existent and historic buildings architecture Attached sunspace

Solar passive solutions compatible with existent and historic buildings architecture Convective loop The thermosyphon effect transfers the heated air in the channel again to the indoor space by an upper vent During the night is necessary to insulate the windows and close the openings

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