QUIZ Fundamentals of Daylighting 1h30

Transcription

1 MIT Architecture Fall 6 Curse 4.4 Daylighting M. Andersen Octber 17, 6 QUIZ Fundamentals f Daylighting 1h Questins pts 3 pts a. Hw wuld yu describe the greenhuse effect bserved inside a glazed space? Hw can we lwer its impact? 2 pts b. What are the varius factrs that make slar time different frm legal time (time indicated by ur watches)? Is there a place n Earth where they are always the same? 3 pts c. Cite the fur majr functins f a windw. Fr each f these functins, cmment n the respective advantages and draw-backs f three types f penings fr a building in Bstn: a clear glass windw at eye-level; a translucent clerestry; a skylight. d. What is the difference between radimetric quantities and phtmetric quantities? Hw are they related t each ther? e. Yu have been hired as a cnsultant t imprve the lighting cnditins in an ffice space. The client cmplains that there is nt enugh daylight in the deepest parts f the rm. What are five prperties f this space yu will first want t assess because they might be critical nes t change t imprve the daylighting cnditins inside? f. What is the definitin f the Daylight Factr? Why is it such a cmmn daylighting metric tday? What are its limitatins in terms f assessing the daylighting cnditins inside a space realistically? Prblems pts 1. The classrms f the elementary schl Ai Saleggi in Lcarn, Switzerland, designed by Livi Vacchini in 1978 and illustrated in figure a are articulated int a zne f frmal teaching and an adjacent ne f mre infrmal activities (see figure b). Yur sn is ging t that schl and tells yu that his pr grades are mainly due t direct sunlight in his eyes whenever he takes a test. Determined t d smething abut the situatin, yu start a sunlight penetratin analysis frm where he sits i.e. secnd rw, n the left side f the class (figure b). 1/6

2 There are skylights n the ceiling and the wall he faces is cmpletely glazed, but his view is partially bstructed by the adjacent classrm and the mvable panel separating the frmal and infrmal prtins f the classrm (see figure b). Yu decide t cncentrate n assessing sunlight penetratin thrugh the prtins f the sky that are visible t him, either thrugh the skylight situated at the frnt f the class, n the left side, r thrugh the glazed wall. The rientatin f the classrm is given in figure c. Image remved due t cpyright restrictins. a. Ai Saleggi elementary schl (image taken frm b. View f the interir f a classrm frm yur sn s desk c. Schl site (sn s classrm in black; lks tward S-E) Figures by MIT OCW..5 pt Start by determining the limit angles fr sun penetratin twards yur sn s eyes by using the plan and sectin views given in figure d. i) Prvide values fr all eight angles: name α1 and α2 the limit elevatin angles thrugh the glazed wall, β1 and β2 the limit elevatin angles thrugh the skylight (fr α1, α2, β1 and β2, use the sectin view), γ1 and γ2 the limit azimuth angles thrugh the glazed wall, δ1 and δ2 the limit azimuth angles thrugh the skylight (fr γ1, γ2, δ1 and δ2, use the plan view). 2/6

3 2.5 pts ii) Reprt these angles n the shadw prtractr given n the next page. Separately fr the skylight and fr the glazed wall, darken the areas crrespnding t sun directins fr which there is n sunlight penetratin twards yur sn s eyes. Then, reprt these areas n the prvided tracing papers. skylight glazed wall d. Plan and sectin views with superpsed prtractrs skylight glazed wall mvable panel Superpse yur shaded tracing papers adequately n the steregraphical view belw (which crrespnds t the latitude 44 N f Lcarn; the fur façade rientatins f the classrm are indicated by the lines crssing in the centre) s as t be able t tell at what times and n what days yur sn might indeed be disturbed by glare. 3 pts iii) Indicate these perids f time by hatching the areas they crrespnd t n the steregraphic chart itself (with clear limits and indicatins; please hand ver the next page at the end f the quiz, with yur name n it) and prvide cmments abut these critical mments. Is yur sn trying t fl yu r will yu invite Livi Vacchini t take this class next year? iv) Fr a perfectly vercast day, clsely fitting CIE vercast sky mdel, abut hw much brighter r darker des the sky appear t yur sn depending n whether he lks at the sky thrugh the skylight r thrugh the glazed wall? 3/6

4 9 9 Name: 9 Skylight 9 Glazed wall Augt 31 Juilll 21 Sept 23 Juin 21 Oct Mai 26 Feb 26 Avril 14 Mars Nv 27 Jan 16 1 Dec Latitude 44 Nrd Figures by MIT OCW. 4/6

5 2. The expsitin rms f the Kirchner Museum situated in Davs, Switzerland and designed by Gign and Guyer in 1992 benefit frm abundant natural lighting thanks t a cmbinatin f lateral glazings n the upper prtins f the façades and translucent ceilings. Images remved due t cpyright restrictins. Kirchner Museum: utside and inside views In museums, a careful cntrl f natural light is critical t ensure the prtectin f lightsensitive artwrk. Befre a final decisin is being made abut adding sun prtectin devices, yu decide t assess the lighting cnditins f the expsed artwrk with a luxmeter. Fr this assessment, yu chse an exhibit space fr il paintings and g arund the rm taking vertical illuminance measurements. Of curse, yu are nt allwed t put the luxmeter flush against the paintings r yu will be thrwn ut f the museum, s yu chse lcatins arund them n the walls. 5 This is the average reading yu get, in klux:.5 pt 1.5 pt 1.5 pt 2 pts Figure by MIT OCW. i) Wuld yu say that this is a gd apprximatin f the illuminance f the il paintings? ii) What is the average luminance f the walls if their reflectin cefficient is.75? Is this luminance a gd apprximatin f the luminance f the il paintings? iii) Assuming that the illuminatin is mainly due t daylight, hw many W/m 2 d yu think the paintings receive, in average? Yu did sme preliminary research and fund ut, frm the IES Lighting Handbk, that the maximum recmmended illuminance fr il paintings was f lux. Yu als fund ut that il paintings can stand an illuminance f lux fr abut, hurs withut being damaged i.e. abut 29 years if expsed hurs per mnth, iv) Hw lng can the painting in this exhibit hall be subject t the measured lighting cnditins withut risk? Same questin if subject t the recmmended lighting cnditins. 5/6

6 Yu ntice a small dark rm, that cntains ne painting illuminated by an incandescent lamp (pint surce). Yu are interested t knw what the illuminance at the center f the painting is and t determine this, place yur luxmeter belw it, as illustrated here: Yu read (in lux): lamp 1 ft 2 ft 4 ft painting Figure by MIT OCW. luxmeter 3.5 pts v) What is the illuminance at the center f the painting? vi) Is this painting safe as far as light-induced damages are 1 pt cncerned? Is this surce a gd chice frm an energy cnsumptin standpint? 6/6