SET. Solar control of extensively glazed facades. a computer method for predicting the effects of various devices and building s thermal inertia

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1 SET 2017 BOLOGNA Solar control of extensively glazed facades a computer meod for predicting e effects of various devices and building s ermal inertia Antonio CARBONARI 1 1 Università IUAV di Venezia, Dorsoduro 2206, Venezia (Italy), carbonar@iuav.it Abstract: Many temperate climates, like most Italian ones, are characterized by considerable daily temperature ranges. In ese cases, e ermal inertia of e building has a significant influence on e management of solar and internal heat gains; en on e energy demand for HVAC, is is especially true in e cooling period. Winter and summer requirements regarding ermal inertia may be in conflict wi each oer, in particular when e use of e building is discontinuous, as in e case of offices. A lower ermal inertia can allow a more rapid heating in e morning and minor nocturnal losses during e winter, whereas a higher inertia may allow a slower daytime heating and a better exploitation of night free cooling during e cooling period. In is study, a typical office room has been studied by means of computer simulations. The only external wall of e room faces sou and is entirely glazed; erefore, it requires e use of some device for solar control. Relatively to is room, e combined effects of some different solar control strategies and ree constructive technologies, characterized by different ermal inertia, have been explored. A first strategy is based only on e use of an internal reflecting and diffusing screen, a second on e use of external movable slats, a ird on e use of small slats inserted between e glasses. Strategies based on e two types of slats can be integrated wi e use of an internal diffusing screen. Computer simulations were performed using a software at allows simultaneous analysis of energy and comfort issues, automatically taking into account any control action aimed at maintaining e ermal and luminous comfort. They were used climatic data of Gorizia, in e Nor East of Italy. Simulations results show at e ermal inertia has a great influence on energy demand and on ermal comfort. The strategy based only on e inner screen is e least advantageous from all points of view. Between e two types of slats, e external ones allow a better ermal comfort, while e oers provide a better visual comfort. Keywords: Solar Control, Energy Saving, Comfort

2 16 International Conference on Sustainable Energy Technologies SET of July 2017, Bologna, IT 1. INTRODUCTION Many temperate climates, like most Italian ones, are characterized by considerable daily temperature ranges. In ese cases, e ermal inertia of e building structure has a significant influence on e management of solar and internal heat gains, en on e energy demand for heating, ventilation and air conditioning (HVAC), especially in e cooling period. Winter and summer requirements regarding e ermal inertia may be in conflict wi each oer, in particular when e use of e building is discontinuous, as in e case of offices. Lower ermal inertia can enable a more rapid heating in e morning and lower nocturnal losses during e winter, while a higher inertia may allow a slower daytime heating and a better exploitation of night free cooling during e cooling period. However, e possible energy savings due to inertia depend on e energy balance of e building as a whole, in particular by its heat gains. In is study, a typical office room has been studied by means of computer simulations. The only external wall of e room faces sou and is entirely glazed, by a double glazing; erefore it requires some devices for solar control. Relatively to is room, e combined effects of some different solar control strategies and ree constructive technologies have been explored. A first strategy is based only on e use of an internal diffusing screen, a second on e use of external movable slats, a ird on e use of small slats located between e two glasses. Strategies based on e two types of slats can be integrated wi e use of an internal diffusing screen. The different building technologies are characterized by a different weight of elements, erefore by a different ermal inertia. In e first case it is assumed at e room is located in a building wi reinforced concrete structure, in e second case in a new building wi light steel structure, in e ird case it is hypoesized e reuse of a building wi heavy structure. Computer simulations have been performed using e Ener_Lux software, at allows simultaneous analysis of energy and comfort issues, taking into account automatically any control action aimed at maintaining ermal and visual comfort. In any examined case, e control logic of e solar control devices is aimed to ensure bo e ermal and luminous comfort inside e room. Simulations are related to e temperate climate of Gorizia, in e noreast of Italy, which requires bo winter heating and summer cooling, in bo e cases ere are no negligible daily temperature ranges. 2. THE CASE STUDY The case study consists in an office room of medium size: 5.88 m wide along e façade, 6.18 m deep orogonal to it, wi internal height equal to 3.27 m. The only external wall of e room is one of e shortest, it faces sou and it is entirely glazed. All e oer five internal enclosing surfaces are considered as adiabatic. In is study e shading effect of surrounding buildings has not been taken into account (Figure 1). Figure 1: The office building wi external slats array and e geometric model of e examined room To avoid excessive internal gains and to study e behaviour of e system even wi positive loads, i.e. under heating operation mode, it is hypoesized e presence of only two occupants wi related equipment. Therefore e internal gains of e room consist of sensible and latent heat flows from: occupants (2 people 65 W of sensible ermal power and 65 W latent), office devices (2 computers and 1 printer for a time average total power equal to 150 W) and fluorescent lamps (luminous efficacy: 91 lm/w, maximum total power: 732 W). The lighting plant is divided into two zones along two bands parallel to e glazed wall and dimmers control e power of e lamps. Adopting ese measures, e annual saving in lighting energy consumption, compared to a park lamps undivided and controlled according to e on/off logic, is 32%. However, if we consider e effects of internal gains 2

3 from lighting on consumption for HVAC, e total saving is 53%. This in e case of e room wi light structure and equipped only wi external slats. Alough is configuration of lighting plant is not very widespread, it was considered appropriate to foresee some form of localized lighting control; oerwise, e ignition of e entire park lamps wi fixed power, due to a small lack of illuminance in one of e workstations, alters heavily e energy balance of e room. To study e ermal and lighting comfort, four possible occupants positions at different distances from e glazed surface were considered. To calculate e primary energy demand related to HVAC, it is assumed at e room is equipped wi a full air centralized loop, and e daily time of utilization is from 08:00 to 19:00, but e plant is activated at 07:00. Alough it is not e best efficient solution, it is assumed at e warm fluid is provided by a gas-boiler and e cold fluid by an electrically driven chiller (vapor compression chiller). Since ese are e solutions currently most widespread in Italy. Internal set-point air temperatures are assumed to be 20 C in winter and 26 C in summer (as prescribed by e Italian law), whereas in half-seasons it is assumed equal to e average daytime external temperature, since e cloing of e occupants is adapted to it. The relative humidity set-point is assumed equal to 50% all over e year. Normally e control systems of HVAC plants assume e indoor air temperature as an indoor environment control parameter, but, in order to study optimal ermal comfort conditions, it s interesting and appropriate to simulate e use of oer parameters, such as e operating temperature (t op) or e average Predicted Mean Vote (PMV) value between e various working places (Fanger, 1970). Alough automatic indoor environment control systems based on ese parameters are not currently available, it can be assumed at is kind of control, in particular at based on PMV, is performed by e occupants when e manual adjustment of HVAC terminals is available. Therefore, in is work, e indoor air temperature was taken as a reference indoor environment control parameters, but e effects of e use of oer parameters, i.e. t op and PMV, were explored Building technologies To explore e influence of ermal inertia on global comfort conditions and energy demand e following building technologies have been simulated. A. Heavy structure in reinforced concrete. Internal walls are in hollow bricks 0.08 m ick, wi 0.02 m ick plaster layer on bo e sides. The horizontal structural elements are reinforced concrete and hollow tiles mixed floors: 0.24 m is e construction ickness, plus 0.06 m of screed and flooring and 0.02 m of plaster in e lower part. B. Light steel structure. The horizontal elements are constituted by a corrugated metal sheet, to which a wooden layer and a wooden suspended floor are superimposed. There are suspended ceilings. Internal partitions are light panels, made of rock wool and plasterboard, and glass walls. C. Hybrid structure. As often happens e office room can be located in a renovated old building wi heavy structure, like at of e previous case A. In ese cases, e internal distribution is changed, and e old partitions are replaced by light dividing elements, like ese of e case B, while suspended floors are superimposed to e existing slabs and suspended ceilings are added, even wi sound-adsorbing features. In all e cases e only external surface of e room is e glazed one, composed by a double glazing of m glass layers, and a m air gap (overall U value: 2 W m -2 K -1 ). Only in e case of slats internal to e glasses e air gap is m ick The Solar Control Devices and eir Control Logics The following solar control devices and related control logics have been examined and compared in reference to e office room. A. Only an internal diffusing screen (a roller blind) wi reflection coefficient equal to 0.5 and transparency coefficient equal to 0.4. Unless oerwise specified, all ese coefficients are taken here wi e same value bo in relation to e total solar spectrum and to e visible range. The infrared radiation (IR) re-emitted from e screen, as well as from any oer surface, is calculated separately, as a function of its temperature and its emissivity. The screen can be lowered eier to limit e solar gain or to avoid glare phenomena. B. Movable external slats in metal. The vertical distance between slats (0.5 m) is equal to eir dep (orogonal to e façade when e slat is horizontal). Slats surfaces are diffusing and eir total reflection coefficient is equal to 0.6 in bo e sides, it would not be realistic to assume a higher value in a normal urban context. Slats are controlled by a seasonal logic, which means: in each moment, slats are inclined at an angle at allows e entry of e only amount of solar energy at can contribute to cover e sensible ermal load, avoiding overheating. In any case, e incoming solar radiation cannot be lower an at required for e 3

4 16 International Conference on Sustainable Energy Technologies SET of July 2017, Bologna, IT daylighting, ensuring a minimum illuminance value in e most critical workplace (i.e. 500 lx according to Italian standard UNI 10380). To prevent glare phenomena two strategies have been analyzed. The first is based on e use of e slats alone, whose slope can be furer increased in order to eliminate glare, even at e cost of sacrificing e daylighting. In e second case an internal roller blind is used. Its reflection coefficient is equal to 0.4 and its transparency coefficient is equal to 0.5. When e blind is lowered, if interior illuminance is insufficient, e slats can be reopened. In all cases, if e daylighting is insufficient, lamps are turned on. C. Small slats in metal (Aluminum) located between e glasses. Only in is case e distance between e glasses is 27 mm. The vertical distance between e slats is 12 mm, eir dep is 16 mm and eir ickness is 0.2 mm. Surfaces are diffusing wi coefficient of reflection for bo e sides equal to 0.7 in e total solar spectrum and 0.78 in e visible range. These slats are packable, apart from at e control logics are e same as used for e external slats. Figure 2: Examples of external slats array, slats inserted between e glasses and internal screen 3. THE SOFTWARE This work has been carried out by means of computer simulations, using software Ener_Lux. This software (Carbonari, 2012) is mainly aimed at e study of solar control devices and related operating strategies. It allows simultaneous analysis of energy aspects and ose related to e ermal and luminous comfort. Therefore it takes into consideration e physical system composed by a room, its glazed surface, internal and external solar control devices (slats, blinds, overhangs and any element shading e opening) as well as e surrounding urban environment, including e building containing e room under investigation. Once defined e kind of devices and eir control logic, e program simulates e dynamic ermal and luminous behaviour of e physical system at hourly time-steps, and provides: Predicted Mean Vote (PMV), Predicted Percentage of Dissatisfied (PPD) (Fanger, 1970) and Daylighting Glare Index (DGI) (Hopkinson et al, 1963) values, togeer wi oer information about e visual environment quality. Then it calculates sensible and latent room s ermal loads and e energy demand for HVAC and artificial lighting. To perform room s energy balance e program use an algorim based on heat balance of elementary zones (e.g. a single layer of a wall or a glass): a ermal grid model. When adjustable devices are simulated, all e solar control actions aimed to maintain ermal and luminous comfort, such as slats tilting or screen lowering, are automatically simulated: in such cases, e program modifies e system s geometric configuration and repeats e simulation of e hourly time-step. The check against visual discomfort conditions is performed only when e lamps are turned off (Figure 3). The indexes used for e assessment of e visual comfort are calculated by means of an algorim simulating, in a simplified manner, occupants visual field (Figure 4). Different kinds of glare are considered: disability glare due to direct radiation impinging on e visual task, big differences of luminance values between different points in e visual field, and discomfort glare due to large luminous sources (typically e sky seen rough e windows) at is evaluated by DGI calculation. When one of ese kinds of discomfort is detected, e program simulates a solar control action. The program allows e use of different indoor environment control parameters: not only air temperature but also operative temperature (to) and PMV. 4

5 climatic data building s description plant s descrip -tion Initially e following elaborations are repeated modifying progressively slats slope until e slope corresponding to e minimum ermal load is found luminous flux on each surface from sun and sky energy radiation on each surface internal gains, excepted lamps internal gains from lamps room s luminous balance, calculation of: - total illuminance (E) on each surface, - luminance (L) of each surface room s energy balance, calculation of: - nodes temperatures - energy fluxes between nodes - room s ermal load yes E min >= 500 lx not check on direct radiation over e visual tasks and occupants acceptable progressive opening of e slats array, until E min >= 500 lx. If possible e slats are packed. If E min remains < 500 lx lamps are turned on DGI max <21 yes not not acceptable diffusing blind lowering E min >= 500 lx not yes check on ermal comfort not OK adjustment of set-point temperature OK over e definitive configuration: calculation of plant s load and primary energy demand Figure 3: Scheme of e Ener_Lux calculation flow. The figure shows e behavior of e program when referring to a slat array combined wi an internal screen Figure 4: Examples of simplified simulations of occupants visual field in different workplaces 4. ANALISYS OF THE RESULTS The solar control strategies have been compared from different points of view: room s total primary energy demand, ermal and visual comfort. Therefore, e ermal flows provided to e room by e plant, are converted into primary energy as a function of current value of boiler efficiency, chiller coefficient of performance (COP), and global system efficiency. The electric energy absorbed by e HVAC system as well as by lighting system is converted into primary energy by means of e Italian electric system efficiency (equal to 36%) Energy performance The room under investigation is characterized by relevant internal and solar gains. For is reason, e cooling loads are dominant in e composition of its total primary energy demand. In facts, wi e exception of e first hours at some winter mornings, e ermal load is always negative (Figure 5). This ing is evident in e trend of monly energy demand for HVAC (Figure 6), which is strongly influenced by outdoor temperatures, and has e 5

6 higher values in autumn (wi a maximum in October). The maximum in October is due to e combined effect of external air temperature, higher an in spring, and reduced daylighting. The strange peak at can be observed in May is due to e previously illustrated criterion used for e selection of e set-point air temperatures in halfseasons. This criterion can be improved. Figure 5: Room wi light structure, ermal load (W) on January 21 (left) and on July 21 (right) wi different solar control strategies Certainly is situation would change by adopting a different lighting system, based mainly on individual lamps located at each workplace (e related power can be reduced from 732 W to 320 W), but e lighting system simulated is currently e most widespread in Italian office buildings. Effectiveness of e various solar control strategies The less convenient strategy is clearly e one based on using only e internal screen, because of e significantly higher solar gains and e consequent costs for cooling. For example: wi lightweight structure e total energy demand obtained wi it is more an 38% higher an e one obtained wi e strategy based on external slats used alone, and more an 44% higher an at related to e slats inserted between e glasses combined wi e inner diffuser. This strategy can be a feasible solution only in colder climates. Figure 6: Monly primary energy demand (per square meter of floor area) for HVAC and lighting plant wi various devices [kwh/(m 2 floor mon)]. Results related to light structure (left) and to heavy structure (right) All e strategies based on e use of e slats are sensibly less consuming, in particular ose using e slats between e glasses (Figure 6). Total primary energy demand depend on e combined effects of e criteria adopted for e control of e ermal and visual comfort, since in e case study e heat flow emitted by e 6

7 lamps almost always increase e plants loads. In general, e use of e slats between e glasses implies lower consumption for artificial lighting, because of eir greater coefficient of reflection. This saving occurs especially in winter and generally in hours wi low solar radiation. For against is type of slats entails a higher temperatures of e inner glass, erefore a greater heat transmission towards e interior, higher solar gain and higher cooling loads. Combining e two effects, e slats inserted between e glasses result in a total annual consumption slightly lower an e external ones, and eir advantage is due to lower consumption for lighting. Of course, ings would change wi a less deep room or wi a different park lamp, based on individual lamps. Comparing e two planned strategies to prevent glare e following can be observed. When it is foreseen e use of an internal screen, it is lowered mainly in e winter and in some morning and evening hours of e oer periods. That is to say: when e sun pas are lower and slats do not intercept direct radiation to consent daylighting. In ese cases, e incoming solar radiation is greater an at request from energy balance, and heat e screen. Then is strategy leads higher cooling loads compared to e oer strategy, based only on e furer inclination of e slats, especially in e case of external slats. In return, in e same periods e use of e screen reduces energy demand for lighting, because it allows a smaller slope of e slats, us a greater incoming luminous flux. However, in practice e two effects balance each oer. In e oer periods, wi e exception of some morning and evening hours, e screen is not used. This is because e sun s pas are higher, solar radiation is more intense and e slats can intercept completely e direct radiation wiout affecting e daylighting. Considering all e two strategies based on e use of external slats, wi and wiout e internal screen, appear slightly less convenient an e oer two, which are based on e use of e slats inserted between e glasses (Figure 6, 7). Effects of ermal inertia Unlike what usually is believed, regarding e spaces used discontinuously, in e case study e ermal inertia reduces e energy demand (Figure 6, 7). This saving is due to e dominance of cooling loads. In fact a lower inertia would be useful only to obtain a more rapid morning heating in a restricted period of winter, roughout e rest of e year e nocturnal cooling of e masses is useful to reduce e cooling loads. When e building elements have greater inertia, e internal surfaces of e room are heated more slowly during e time of use, wi all e positive consequences on comfort and ermal loads. Figure 7: Annual primary energy demand (per square meter of floor area) for lighting plant (EP L), hot battery (EP HB) and cold battery (EP CB) of HVAC plant wi various strategies [kwh/(m 2 floor mon)]. Results related to light structure (left) and to heavy structure (right) The advantage of e heavy structure is particularly evident, wi an annual saving of about 28%, in e case of e less advantageous solar control strategy: e one based on e use of e only internal screen. The annual energy saving due to increased inertia is 9% wi external slats and 15% wi slats between e glasses, when bo are used wiout e inner screen. Wi e combined use of slats and internal screen e savings became 13% and 18% respectively. The configuration resulting from e reuse of an existing heavy building has very similar performance to e new lightweight building. Evidently, e added cavities are sufficient to make irrelevant e masses of e lower and upper floors in room s heat balance. 7

8 Effects of different indoor environment control parameters Using e oers internal environment control parameters, different from air temperature, e energy demand for lighting remains substantially unaltered, while e one for HVAC increase but not too much. The biggest increases in total annual primary energy demand, respect to at obtained controlling e inner air temperature, are understandably found wi e strategy based on e inner screen alone. Using e.g. e control on spatially averaged PMV value, e increase is 22% wi e light structure and 23% wi e heavy one. Using e same control parameter, in e room wi light structure and solar control strategy based only on e external slats e total annual primary energy demand rises by 10%. Wi e same structure and slats between e glasses, always used alone, e increase is 11.5%. In is way e advantage of e second type of device compared to e first is reduced from 2.4% to 1.1% (Figure 8). Wi e heavy structure, which, as see above, results in lower cooling consumption, e total annual primary energy demand related to e external slats rises by 7%, while e one related to e slats between e glasses rises by 10%. The advantage of e second type of device compared to e first is reduced from 8% to 6%. In general, wi all e simulated internal environment control parameters, e slats between e glasses retain eir advantage due to lower consumption for artificial lighting. Figure 8: Effects of adopting different indoor environment control parameters on total primary energy demand for HVAC and lighting plant [kwh/(m 2 floor mon)]. Results related to room wi light structure, wi external slats (left) and slats between e glasses (right), in bo cases wiout e use of e internal screen 4.2. Thermal comfort If e indoor air temperature is used as e indoor environment control parameter, e differences in ermal comfort, obtainable wi e various devices, are mainly influenced by e mean radiant temperature (MRT), and is parameter is in turn affected by e temperature of e internal side of e glazed wall. This quantity can be eier e temperature of e internal glass an at of e screen, when it is lowered. The differences in e PMV value between e various workstations are greater as e inner temperature of e glazed wall differs from at of e oer interior surfaces. Figure 9: PMV values near e glazed wall on January 21, wi light structure (left) and heavy structure (right) Comparing e different solar control strategies, e worst results, at is e higher values of PMV and e lower values of its spatial uniformity, are obtained wi e inner curtain used alone, because of e high temperatures at it reaches when it is irradiated, i.e. over 33 C in July (Figure 9,10). Between e two types of slats, whose internal to e glasses in general maintain higher e temperature of e inner glass, erefore e MRT and e 8

9 PMV are higher, even e spatial disparity of PMV values is greater (Figure 11). However, when e screen is lowered it is irradiated and reaches higher temperatures an ose of e inner glass, and is, as seen before, occurs more frequently wi e external slats. In is case ere are no remarkable differences between PMV values obtained wi e two types of slats. Figure 10: PMV values near e glazed wall on July 21, wi light structure (left) and heavy structure (right) Comparing e different constructive technologies, e heavy structure tends to keep e temperatures of e inner surfaces lower, including at of e glass. This occurs for most of e time, except at in e early hours of e morning in e coldest period. In is way, e PMV assume values closer to ose of comfort and e differences between e MRT obtained wi e various devices are attenuated. However, e spatial differences between PMV values increase when e temperature of e inner surface of e glass is higher. Figure 11: Daily average differences between maximum and minimum PMV values inside e room (in point of PMV), wi light structure (left) and heavy structure (right) 4.3. Luminous comfort To evaluate visual comfort ey have been considered mainly two types of glare: at due to solar direct radiation impinging on visual tasks (at is a kind of disability glare) and at due to e presence of extended light sources in e visual field of e occupants (a kind of discomfort glare). In is case e extended light sources is e sky seen rough e glass wall. This last kind of glare is evaluated by e DGI index, e limit value of which is assumed equal to 21, according to Italian standard (UNI 10840). It is also calculated e uniformity factor of e illuminance wiin e room (CU), which is defined as e ratio between e minimum and e average values of illuminance on visual tasks. To calculate e DGI value, for each position e worst line of sight is considered, i.e. e one implying e greatest difference in luminance wiin e visual field. Thus, e glazed surface must be present in it, but it is empirically assumed at it cannot occupy more an half e visual field; oerwise e occupant s eyes adapt emselves to e luminance of e external landscape. In e case study, e first kind of glare occurs only wi e configuration devoid of slats and in e workplaces nearer to e glass wall. This kind of glare can be connected wi ermal discomfort too, because of e direct radiation impinging on e occupants. Even e worst value of DGI and CU are obtained wi is configuration. 9

10 In presence of slats only e second kind of glare, due to extended light sources, can occurs, and is happens more frequently wi external slats, in e winter and in general in e hours characterized by a reduced radiation s intensity. In ese periods, because of eir lower reflection coefficient, e external slats assume a slope minor an at assumed by e slats between e glasses, consequently e visible sky is more extended and DGI value is higher. This requires control actions at can imply a reduction of internal illuminance, en e use of artificial light. In e same periods e slats between e glasses provides better CU values too. In e oer periods, excluding some morning and evening hours, not are remarkable differences between e DGI values obtained wi e two types of slats. In bo cases, slats assume high slopes to fully intercept e direct radiation, so e bright sky is not visible. In ese periods, e main daylighting source is constituted by e internal slats surfaces, which is brighter in e case of slats between e glasses; consequently, wi is kind of slats e DGI value may be slightly higher, however wiin e limits (Figure 12). Figure 12: DGI values in a workplace near e glazed wall wi different devices, on December 21 (left) and July 21 (right). Values are calculated after e control of solar gain and before e actions finalized to avoid glare 5. CONCLUSION In e case study, e solar control strategy based on e inner screen alone is e less convenient from all points of view, because of e higher solar gains and less uniform distribution of incoming radiation on e internal surfaces. There are not large differences in total energy demand between e two types of slats studied. While e slats inserted between e glasses imply higher solar gains, en higher cooling loads, for most of e time, e external ones imply minor internal illuminance values, us greater energy consumption due to e lamps and related heat gains. Combining e two effects, e slats between e glasses entail a slightly lower total annual primary energy demand, and eir advantage is due to less use of e lighting plant. In general e slats inserted between e glasses imply higher temperature of e inner glass, erefore, if it is not used an internal screen to avoid glare, is type of device results in lower ermal comfort for most of e time. The use of e PMV, instead of indoor air temperature, as an indoor environment control parameter, implies higher cooling loads, en higher energy consumption for HVAC. However, e increase of total primary energy demand is considerable (up to 23%) only in e case of e strategy based on e inner screen alone. Wi all e oer strategies, is increase is wiin 12%, and ere are not significant differences between e two types of slats. The slats between e glasses maintain eir small advantage, even if slightly reduced. In e winter, and in general in e hours characterized by a reduced radiation s intensity, like some morning and evening hours, e slats between e glasses allows a better visual comfort. Contrary to what is usually believed about e spaces used in a discontinuous manner, in e case study wi all e examined solar control strategies, a greater ermal inertia reduces e energy demand for HVAC. This is due to e dominance of e cooling loads. Even ermal comfort improves wi increasing inertia. 6. REFERENCES CARBONARI, Antonio, Thermal and luminous comfort in classrooms: a computer meod to evaluate different solar control devices and its operating logics. In: PLEA The 28 rd Conference, Opportunities, Limits & Needs Towards an environmentally responsible architecture. Lima, Perù, 7-9 November [online] Lima: PUCP. Available at: [Accessed 8 May 2017] FANGER, Povl Ole, Thermal Comfort. New York: Mc Graw-Hill HOPKINSON, Ralph Galbrai, PETHERBRIDGE, P. and LONGMORE, James, Daylighting. London: Heinemann 10