ERASMUS IP Sustainable Refurbishment, Retrofit, Energy Management in Housing

Passive solar systems for building renovation

Maria Isabel Abreuisabreu@ipb.pt19th 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

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

There are some passive solutions that are possible to apply

Key passive solar building design concepts

Direct solar gain

South facing glass

Thermal mass to absorb, store, and distribute heat

Insulation and glazing

Indirect solar gain

Passive cooling

Isolated solar gain

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

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

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

Direct solar gain/Heat storage

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

Thermal storage walls – Trombe walls

Indirect solar gain/Heat storage

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

Isolated solar gain

SunroomsConvective loop through an air collector to a storage system inside the building

SunroomsConvective loop through an air collector to a storage system inside the building

Isolated solar gain

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

Sunrooms

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

Insulation

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

Special glazing systems

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

Passive cooling

Preventing heat from entering the interior (heat gain prevention)

Removing heat from the building (natural 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

Passive cooling

Window coverings are material used to cover a window to manage sunlight

Curtains / Drapes

Window blindsVenetian blinds: Wood, Faux Wood, Vinyl, AluminumMini blinds

ShuttersWindow Shades, including:

Roman & Folding ShadesRoller Shades

Solar screen

Window coverings

Window coverings

A solar chimney or thermal chimney

Passive cooling

Is a way of improving the natural ventilation of buildings by using convection of air heated by passive solar energy

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

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 cooling

Sunrooms can also be designed to perform this function

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

Passive solar lighting

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

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

Relocate poorly orientated or oversized windows and increase the size of solar exposed south

windows

Use high performance windows and glazing for all

new windows and doors Replace poorly performing windows where possible

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

Implement dark external floor finishes

Double glaze windows to reduce winter heat loss

RenovationCreate airlocks at entrances in cool and cold climates

Add doors and walls to create zones with

similar heating needs

Reorientate as much of the living space as possible to

the south side South-facing bedrooms can

become living rooms

Seal existing windows and external doors, and replace

warped or poorly fitted doors

And more…

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

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

Thank You